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“Surgical challenges in the management of nephroblastoma" Dr Derek Harrison, Paediatric Oncological Surgeon, Johannesburg, South Africa



In this on-demand teaching session, you will listen to an in-depth discussion on surgical challenges in the management of nephroblastoma by renowned specialist pediatric surgeon, Dr. Derek Harrison. With 13 years of experience as the Acting Head of the Department at Baragwanath Hospital and an affiliation to Wits University in Johannesburg, Dr. Harrison has significant expertise in pediatric surgical oncology. His research projects with the South African Children's Cancer study group, Oxford University Saint George Hospital in the USA, and his membership in the International Pediatric Society of Oncology contribute to his distinguished standing in this field. His practical experiences and knowledge will shed light on the intricacies of treating nephroblastomas and strategies to overcome associated hurdles. The discussion will also touch upon the broader challenges related to pediatric oncology care on a global scale, especially focusing on Africa. Whether you're seasoned medical professionals or budding healthcare specialists, this session will provide substantial insights beneficial for your profession.
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This is an invited talk on the "Surgical challenges in the management of nephroblastoma" by Dr Derek Harrison, Paediatric Surgeon @ Chris Hani Baragwanath Hospital & WITS University, Johannsburg, South Africa as a part of Zoom academic meetiong of the department of Paediatric Surgery in East London, South Africa.

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Learning objectives

1. Objective 1: Understand the global disparity in the incidence and survival rates of nephroblastoma in different countries and regions. 2. Objective 2: Understand the role of the World Health Organization and Saint Jude's Children's Hospital's Global Initiative for Childhood Cancer in combating nephroblastoma. 3. Objective 3: Learn about the strategies employed by the Collaborative Wilm Tumor Africa Project to increase survival rates in Sub-Saharan African countries. 4. Objective 4: Understand the typical approach to the medical management of bilateral Wilm's tumors, including the role of neoadjuvant chemotherapy and nephron-sparing surgery. 5. Objective 5: Learn about the unique surgical challenges posed by bilateral Wilm's tumors and IVC thrombus, and how these challenges can be addressed in a clinical setting.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

OK, greetings to everybody. I see most of us are from South Africa. So I'll say good afternoon or good evening. But a few other colleagues may join from uh the rest of Africa or rest of the world. So uh welcome uh to, to the uh tonight's uh uh zoo Academic meeting of the Department of pediatric Surgery in East London. And today we are going to have a very uh scholarly and interesting talk on surgical challenges in the management of nephroblastoma by Doctor Derek Harrison. And uh for those of us in South Africa, I don't think Doctor Harrison needs any introduction, but for younger ones who uh don't know him, Doctor Harrison did the undergraduate and postgraduate that general surgical training in Zimbabwe. And he was inspired by his consultant there. Uh and, and sort of motivated uh he got motivated to do pediatric surgery training. Uh further, he came to South Africa and did pediatric surgery training in Cape Town and being a foreign qualified doctor like me, he had to go through a difficult route of getting uh the examinations done and registering as a specialist pediatric surgeon. He's currently the acting head of the department at Baragwanath Hospital which is affiliated to the Wits University in Johannesburg. He has been there for past 13 years. His special interest obviously is pediatric surgical oncology. He is a member of the International pediatric Society of Oncology. And um probably luckily his partner, Doctor Naidu is also a pediatric radiation oncologist and I had the pleasure of meeting his beautiful family. Um when doctor um uh sorry, I probably skipped one. Sorry. He, he uh is involved in research projects with the South African Children's Cancer study group with Oxford University Saint George Hospital in USA. Um And uh um a global initiative for children's surgery. The Giggs group, he is interested and has started collaborating with the LIS. He was the member of the organizing committee of the inaugural I PSO Africa conference which was recently held in Uganda. He is involved in undergraduate and postgraduate teaching and he has been an examiner for the Fellowship of pediatric surgery exam in our country and uh for the oral as well as for the return component. When doctor uh Harrison is not working hard, he um is, is a proud father. Um and, and a sportsman. He has submitted Bound Kilimanjaro in 2014. He played Judo for Ken and for Zimbabwe. And he says that he enjoys learning the fine art of dancing with his little Princess Tahira. So with all this introduction, I will stop screen share and I'll invite doctor Harrison to share his experience about nephroblastoma, the challenges in the surgical management, correct? Uh Thanks Melin. Ok. Ok. II assume that you can see my screen. Yes, I can see your screen and I can hear you nicely. You can. Ok, great. So, um yeah, if I, if I run on a little bit too long, if I ramble a bit too much and you can just stop me. So I see it's, it's five past now. Um And so, you know, so I'm talking about the challenges in the management of nephroblastoma. And I know you uh hosted an excellent talk earlier this year um with one of your colleagues from India. And I know Larry also had a lot of input in the conversation around that. So I hope that, you know, to do, to do that uh justice and, and present some things I thought, um you know, I was also gonna talk about, you know, massive worms and the pulmonary metastases math, but I think the information might just be a bit too much. I'm talking about bilateral worms and IVC extension. But I thought, you know, I started off and I thought I'd just also touch on global challenges and I'll just present some of our sort of the, you know, the global aspects around um you know, pediatric oncology in, in Africa. And um and I know also Larry Hadley had a lot of experience in this as well. So I'm looking forward to the discussion afterwards. Um So let's just, I just wanna touch on some global challenges initially, right? So, um so, I mean, as we know Africa disproportionately bears the burden of childhood cancers globally. And although the continent only contains 16% of the world's population, it makes up 23% of the global childhood cancer cases. And this is because 41% of its population is under 15 years and um there are disparities in five years survival from, for example, only 8% in Eastern Africa to as high as as 52% in South Africa. And it is estimated that only 57% of childhood cancer cases are formally diag diagnosed. And this is, you know, due to access to specialized pediatric oncology care. Sorry, I'm just struggling to. Ok. And then you, you know, if we look, I mean, this is a recent paper in 2019. If we look at 54 countries in Africa, 20 don't have full time pediatric oncology physicians. 23 have active pediatric cancer clinical programs, five have fellowship programs and uh several have actually started clinical cooperative groups. Um The South African Children's cancer study group was founded in 1987 and, and this was to coordinate pediatric cancer care and play a role in advocacy in the region. A registry was started to keep records of the types and outcomes of the various malignancies and from 97 to 2007, whilst leukemia lymphoma and brain tumors formed the bulk of the total malignancies in Children. I mean, the extracranial solid tumors made up 38% of the total. And these comprised of nephroblastomas, making up 12% of them followed by sarcomas and neuroblastomas, germ cell tumors and, and liver tumors. Um So this is uh an excellent paper, I mean, and there's many more like this but um you know, I don't bring them up on my screen but they're actually referenced. But there's one by Larry Hadley talking about the challenge of pediatric oncology in Africa. And he sums it up saying that the challenge of pediatric oncology is in Africa is compromised by an inadequate healthcare in Children, presenting with a advanced local and metastatic disease as well as multiple comorbidities. Pediatric surgical oncology is not yet regarded as a health care priority by governments trying to achieve their millennial goals and improving surgical expertise alone, which is what we try to do with ourselves, will not compensate for the major infrastructure deficiencies but must proceed in tandem with resource development. The wh O said that uh in high-income countries, 80% of Children with cancer survive as compared to 20% in low and middle income countries. However, only 20% of all cancers occur in high-income countries, whereas 80% occur in low and middle income countries, albeit many or unreported. This is a map showing your estimated rate per million of cancer incidents in the in Children. And you can see in the North America, Europe and Oceana, they got the high highest incidence but mortality is only ranging from 23 to 31 per million. Whereas in Latin America, Africa and Asia, the incidence was lower, but the mortalities are higher from 43 to 50 per million patients. So the the wh O and Saint Jude's uh Children's Hospital um have a global initiative for childhood cancer, which was launched in 2018. And this aims to double the global cure rate for Children with cancer to at least 60% by 2030 thereby saving an additional 1 million lives. The initiative has two aims and firstly is to increase the capacity of countries to deliver quality services for Children with cancer. And secondly, to increase the prioritization of childhood cancer at global regional and national levels. The plan is to initially target six common malignancies prevalent in all countries that represent 50 to 60% of all childhood cancers with highly curable improvement therapies and nephroblastoma is one of the index cases with a high prevalence in Africa. Um A recent study on global disparities in nephroblastoma found that the incidence is highest in low-income countries. The overall survival range from 70 to 97% in high-income countries as compared to only 25 to 53% in low-income countries in Africa. The data showed that malnutrition, lack of patient education, lack of finance and drug shortages played a role in mortality. The S PO Committee po as pediatric oncology in developing countries ran a project which adapted relatively simple and low-cost treatment guidelines for nephroblastoma in six centers in Sub Saharan Africa, known as the collaborative S Tumor Africa project. The aim was to increase survival to over 60% in in line with the WH O Global initiative for childhood cancer funding was distributed to all centers to cover treatment, travel counseling and other associated costs. And the project was associated with a significantly higher two-year diseasefree survival from 52 to 68% reduced abandonment from 23 to 12% and fewer deaths during treatment from 21 to 13%. Um A a study in South Africa calculated the overall survival rate of Children with cancer to be 52%. Uh lymphoma, nephroblastoma having the highest survival rates at 64 and 63%. While brain tumors is the lowest at 46%. And they actually attribute survivals to Children presenting with advanced disease. For example, survival in stage one, nephroblastoma was 80 to 81% for stage four. It was almost half at 46%. But these are just some survival curves of studies that have been done in South Africa, which have showed improved survival from 62 to 86% you know, effectively after changing treatment protocols from upfront surgery to neoadjuvant chemo and um as, as as their treatment protocol and the recent study that we did in Johannesburg shows an improved survival of up to 85%. Um And just to end off on sort of our, our global aspect or um the aspect of uh nephroblastomas in lower to middle-income countries. And, and um and mi already mentioned this. So this year, you know, we had the 14th Congress of South Africa. Now this is held every second year, but this year it was the inaugural IP SA Africa in the surgical body to have their conference, which um which I was part of the, the organizing committee which is shown here. And I just want to point out so it was, was the inaugural meeting. It was a one day workshop and it was very successful. I just want to point out that in two years time. So in 2024 it's actually gonna be held in, in South Africa. So if people can just add that to their diary. So now I'm gonna get on to like surgical challenges. So I must talk about bilateral worms and then I'm gonna talk about IVC Thrombus. Um So historically, the management of bilateral worms was not standardized and suffered from instances of prolonged chemotherapy and inconsistent surgical management which resulted in some optimal renal and oncological outcomes. Neoadjuvant chemotherapy and Nephron sparing. Uh uh surgery have been adapted as the guiding management principles. The coordination of neoadjuvant chemotherapy and the timing and implementation of bilateral Nephron sparing surgery requires collaboration between oncologists and surgeons. When we now look specifically at the medical management for bilateral worms, tumors, otherwise known as stage four, which occurs in about 5 to 10% of synchronous and maybe metachronous up to about 1% both S and the um International Society for Pediatric Oncology. And um K is the children's oncology group from North America. So both of them suggest six weeks of neoadjuvant chemotherapy, followed by reimaging for Nephron sparing surgery of at least one kidney. And if only a partial response, then they repeat the chemo and they do it for another six weeks and they do definitive surgery at 12 weeks. Um However, a patient was suspected bilateral worms having the typical age, which is greater than six months, but less than seven years and imaging findings will not require diagnostic biopsy as it will be upstage to a local stage. Three. Um You know, this is because the worms, your national worms tumor studies four and five have shown that unfavorable histology has been missed on the initial biopsies. Um However, children's oncology group will advocate for an open biopsy if there's less than 50 50% partial response and they can't do nephron sparing surgery at six weeks. Um These guys, all these guidelines also deal with nephroblastomatosis or unilateral worms or horseshoe kidneys or any predisposition um syndromes. So, the aim is to achieve high cure rates while preserving as much functional renal tissue as possible. And renal outcome has significantly improved after bilateral nephron sparing surgery compared to other types of surgery. So, for example, endstage renal disease um occurs in about 9 to 12% of, of your patients that increases with up to 50% resection and actually up to 20% in upfront surgery. I mean, and, and, and you know, for example, to put this in perspective, if we do a, just a unilateral nephrectomy and unilateral tumor, it's, it's about a quarter of a percent. Um So the strategy is to give frontline chemotherapy to decrease the volume as much as possible, then to do Nephron sparing surgery as often as possible. And then your adjuvant therapy is adjusted to the highest histological type and local stage of the tumor. Low dose radiotherapy 10 gray, for example, may result in long term remission after incomplete excision uh without altering the renal function too much that has hard, largely been avoided because of radiation injury to the residual renal mass. So this is a comparison between the siop and the children's oncology group. Um I don't know if you can see my error here on, on the SA group, but the difference is they, they both give chemo for six weeks. S aab give two drug chemotherapy. Um the Van Actinomycin and the, the cog group A and DOXOrubicin after six weeks, reassess. And they're looking, if they can do Nephron sparing surgery. Ideally, the cog uh try to do bilateral nephron sparing surgery. But if they feel it's not feasible, they're gonna give another six weeks cop. There is provision to go and do a unilateral nephrectomy and Nephron sparing surgery on the other side. Otherwise you carry on for another six weeks with your chemo. The. However, in the C group, if it, if there's poor response or stable disease or progressive disease, then they will change the chemotherapies and add in uh ops and carboplatin and ifosphamide the Americans here at this point, after six weeks will do a biopsy to see what they're dealing with. And if it's an a plastic histology, they modify their regime. If it's more predominant, they, they modify their regime. However, 12 weeks, then you go for your surgery, preferably bilateral nephron sparing surgery or unilateral uh radical nephrectomy with uh contralateral N SS. So when we do imaging on these tumors, we do, you know one of the best things is a CT scan or 3 3D reconstruction to visualize the vascular pedicles and collecting system and to assess the feasibility of N SS MRI seems a little bit more sensitive to differentiate nephroblastomatosis from Wilms tumor. Um But we must also do a renogram. So we can look at the differential function on each side and work out the, the G FR they do talk about pet CT scans, but these are more to distinguish between active lesions and scars. But you can't really tell the difference between nephroblastoma, tissue and nephroblastomatosis. So, when we're going to operate or some of our principles and our considerations are we must look at the, the, the tumor size, see if it's more, if it's peripheral or polar located. Um the lack of invasion or encasement of vessels um which will, which will favor a Nephron sparing approach, large tumors, central location and proximity to vessels should not be regarded as an absolute conjugation for N SS. But these are ominous imaging features. When we do the operation, uh we can the sequence of operation, resection can be done in one operation or staged and s surgical resections can be multiple and repeated for one kidney with acceptable oncological outcomes and preservation of renal function. So the types of operations described. So you, you talk about a unilateral total nephrectomy with contralateral partial nephrectomy, providing enough renal tissue can be preserved or a bilateral partial nephrectomy, which is the, the main surgical aim to preserve as much renal tissue as possible. And then the third one is enucleation. There are descriptions for unilateral total nephrectomy. So you just take out one kidney, you don't touch the other side. A unilateral partial nephrectomy. So you just do N SS on a single kidney. There's bilateral total nephrectomies where you then receive dialysis and transplantation is planned provided no recurrence or residual disease after two years. Um We talk about he nephrectomies or wed resections, but I'll, I'll get on to the standardization and the classification of, of our Nephron sparing surgery. So, def definitions of the surgical approach are unclear, confusing and highly variable. The subject of surgical resection margin is often omitted from reports and assessment of the remaining renal volume of renal parenchyma is are often not included. So, a standardized reporting could more consistently determine associations between surgical technique margin status or long term renal outcomes. And I'll just break up this table and you see. So this table includes number one, the surgical technique. So the definition of partial nephrectomy is resection of the tumor with a room of normal renal parenchyma. And um and you know, and for our um for our documentation, this is called NS SA. So effectively, this this partial nephrectomy is more oncologically sound and this is the procedure of choice when feasible. The second type which is known as enucleation is resection of the tumor along a plane of its pseudocapsule with outer rim of normal para renal parenchyma. This is known as N SSB and this enucleation is acceptable but provided that anaplasia is ruled out otherwise, additional surgery is indicated. When we look at the rest for our standardization, we talk about the re surgical resection margin. So this is the opinion of the surgeon. So he will give it AAA figure if he feels the the the there's an intact pseudocapsule. If he thinks that in it's in doubt or if he knows there's been a tumor breach, these specimens go to pathology and you get a pathological resection margin where they talk about a safe rim of renal parenchyma on the margin. They can then see themselves where there was an intact pseudocapsule on the margin or where there was a tumor breach. And then lastly, the estimation of the remaining renal parenchyma. This is a subjective evaluation done by the surgeon of the percentage of renal parenchyma remaining on the operated kidney. For example, a polar nephrectomy usually corresponds to re remaining tissue of around about 70%. And then this should be reported as follows in that, in that um that equation below. So when we're doing a unilateral total nephrectomy with a contralateral partial nephrectomy, the less involved kidney for NSA should be operated on first, followed by the contra contralateral radical nephrectomy. However, if we're doing bilateral nephron sparing surgery, the kidney with a larger tumor burden is operated on first, followed by the less involved kidney. So ie the most technically challenging component is done first so that you're aware of how much renal function remains before operating on the relatively easy side. Um The the surgical technique, our basic principles when operating is divided up into to six principles and I'll touch on each one of them now. So the first principle is early vascular control. Um So, ideally, tactile feedback is instrumental in identifying tumor margin for, for nephron sparing surgery. Therefore, an open approach is recommended, the kidney is completely immobilized on a pedicle, water from the peritoneal cavity and the main renal artery and vein are dissected and inserted, circled with vessel loops to be used as vascular control in cases of temporary bleeding. However, careful handling of the vascular pedicle is critical because traction injury with vascular thrombosis or spasm can occur manual compression of the renal hilum rather than the vessel or vessel loops of the hilum is readily accessible. So secondly, we want to, one of the second principles is to avoid renal ischemia. So we don't routinely utilize vascular camps or preemptively occlude the renal vasculature, intermittent digital hilar compression can be used to control blood loss and minimize ischemic time. And we don't routinely ligate branches of the renal artery or vein outside of the renal parenchyma hemostasis is achieved by simple finger compression of the immediate surrounding parenchyma. Surface cooling can be used if length of warm ischemia is anticipated for more than 30 minutes. And this has been described in uh cape town with institute topical cooling. Then surgery and autotransplantation are rarely needed. And it's said to be difficult to usually discriminate between tumor nephroblastomatosis and the normal renal tissue. So, the third principle is to get complete tumor excision with negative margins. Um when we perform a partial nephrectomy, if a rim of tissue can be taken. And this is if it's peripherally situated or well localized in upper or lower pole, if not. And a new lesion with an intact capsule. For example, for multiple lesions or large lesions or those with higher involvement. Alternatively, longitudinal partial nephrectomies have been described to approach central lesions where whole kidney where the whole kidney can be bivalved. And this has been described by um a guy in Germany or discrete multifocal lesions are usually independently nated during the operation. Um Any lesions that have responded on preoperative imaging should be biopsied if there is a visible scar and intraoperative frozen section is usually not necessary. Um The fourth principle is precise closure of the collecting system. Um A double J stent or perinephric drains are not routinely used but should be considered when resection involves complex collecting system reconstruction. And the current recommendations is just to leave a, a flank penrose drain as opposed to a double J stent. The fifth principle is achieving uh careful hemostasis. So you can use fine bipolar monopolar Corry, ultrasonic scalpel, um ligasure or any device that you want to facilitate hemostasis. There are three zones of technical repair with the cortex lending itself to Corry hemostasis, the med medulla to suture ligation and the pelvic caliceal system to uh to suture repair hemostasis at the cut surface of the renal parenchyma can be facilitated by applying temporary pressure or Argon beam coul patient or the placement of an absorbable topical hemostatic agent. So, finally, the last principle is closure of the renal defect. Um redundant renal paran comer used to close over the collecting system is used to make sure lymph nodes are sampled for local staging of each tumor. At least one adrenal gland should be preserved to maintain function. Um And if tumors appear unresectable at surgery, the tumors could be biopsied. Um S IOP advocate for core needle biopsy and the cog advocate for open biopsy. Radiotherapy use has decreased over over the last few years. Um and it comes at a cost of reduced renal function, particularly in younger patients. Um radiotherapy is effectively for abdominal stage three tumors or for stage two cases of anaplasia with involved margins. So just to to sum it up in the tips and pitfalls and complications. Surgery includes a staging and includes staging and local control components. Tumor spillage can result in significant therapy, escalation and have prognostic implications. Recurrence of warm tumor might be unsalvageable to achieve an R zero resection, prevent tumor spillage and mitigate complications and resections of other organs. Adherence to adequate lymph node sampling and complete documentation of surgical staging, improves local control strategy and outcome. It is recommended that approximately seven lymph nodes be sampled. Management may also be complicated by the presence of multiple nephrogenic risks, nephroblastomatosis and these are difficult to distinguish from from worms um especially in a case of metachronous presentation where contralateral nephrectomy has already been performed in case of a positive margin. And tumors with diffuse anaplasia completion, nephrectomy followed by flank radiation should be considered. Transplant has historically been delayed until one or two years after cancer therapy because most worms, tumors relapse occur within two years of diagnosis. However, more recent data shows um even those that underwent early transplant, the outcomes are similar. So long term survivals have gone in your NW TS studies from 56% for your, your unfavorable histology to 81% for favorable histology. The C nine talk about an 85% and uh the cog talk about a 95%. So there's been a dramatic improvement in our bilateral worlds based on the principles that I've discussed. I'm gonna move on to the, the last section which is IVC extension and any of the surgical challenges. Um So IVC thrombus occurs in 5 to 15% of the cases depending where you were, you are, reports are different in your, in, in WTS groups, your German groups, UK in South Africa. It's been, it's been described at 10% and often it only involves the renal vein in at least two thirds of the cases. Tumor thrombus may extend up into the atrium in 1% in South Africa. This is 2.5%. Um It's more common 59 to 85% in right-sided tumors because of the shorter renal vein. And then this is just a table from one of Larry Hadley's publications um talking about the management of atrial disease. So when we image IBC extension, so it can be evaluated by MRI which is not routinely used. Could use a CT contrast enhanced CT scan as shown in the diagram and, and colored Doppler, which is the recommended modality for preoperative evaluation because of its high sensitivity and the Doppler should always state the patency of the renal veins and the inferior vena cava. We should also look for retrograde extension into the IVC. The contralateral renal vein, hepatic veins as well as lumbar veins and other tributaries. Echo is an absolute to detect intracardiac thrombus as well as the cardiac function. And transesophageal echo should be used intraoperatively. So when we look at the classification of intravascular thrombus, uh there's two classifications. So this first one is known as the modified uh down classification. Um So where, where your, your stage one is just in the renal vein. Stage two, it's infrahepatic thrombus. Stage three, it's retrohepatic or suprahepatic thrombus. Stage four. It's intraatrial and stage five, it's intraventricular on the right hand side. Another classification that's been described in 2008. Um This is, this is otherwise known, this is described by uh Nite Pado. So he talks about three levels. So this one level one thrombus which is infrahepatic. So it's no longer divided into renal vein or infrahepatic stage one or two. It's just level one, thrombus is infrahepatic. Yeah, level two, thrombus now has 33 different levels A B and C. So your your uh your retrohepatic. So A is retrohepatic B is suprahepatic but infradiaphragmatic and C is suprahepatic supradiaphragmatic. So it looks, it's a little bit confusing. So it's taken one, it's made 11 level, level two, but he is divided in 2 to 3 levels based on where it's sitting in comparison to the diaphragm. And then level three thrombus is saying it is in, in the atrium. So when we look at just the staging, the oncological staging of, of IBC extension, um stage two is when, when the, when there's the renal vein, when there's a renal vein retraction issue. So this is a pathological reporting. So often the thrombus bulges out of the resection line of the renal vein and such cases have to be discussed with the surgeon. And if the surgeon could just pull out the thrombus out of the vessel on block with a tumor, it is just stage two. However, it will be stage three if the tumor thrombus is present at the resection margins, um all the tumor thrombus which is attached to the IBC wall is removed, piecemeal was very a very difficult instrumental removal. So effectively, it can be a stage two if it just slips out easy, no residual tumor, but if it's at the margins or it was difficult removal, and it's a classified as a stage three. So now when we look at the medical management, primary surgery carries the risk of thrombus dislodgement with embolus and acute cardiac decompensation. So both protocols mandate near adjuvant chemotherapy for tumor thrombus extending up to the hepatic vein or above. Cog advocate for upfront surgery when the thrombus is below the hepatic veins. However, neoadjuvant chemotherapy for six weeks and induces thrombus reduction, facilitating resection and may avoid the need for your cardiopulmonary bypass in up to two thirds of patients. Um The primary surgical resection which often requires sternotomy and your bypass with a thrombus extending above the diaphragm was associated with significant morbidity and mortality in the past. And, and your NW TS study four had that at 94%. So, however, further extension of chemotherapy cycles beyond six weeks offers no added advantages. So effectively, you're cutting off at six weeks for your chemotherapy complications may occur. For example, you might get tumors, thrombus ligation, uh progression which may be propagated, just blood clots. You may get a, a rupture, you may get an embolism. You may go into cardiac failure and have acute respiratory distress syndrome surgical complications and occurred in 37% in the atrial group and 17% in the IVC group. And the frequency of surgical complications was 26% in the primary resection group versus 13% in the Children in the pre with the preoperative therapy. So, effectively, you're having your complications um with your neoadjuvant or if it's lower down in the ABC. Um when we talk about prognosis, the thrombus itself does not affect prognosis as long as it's successfully resected and there's no difference in your. So your three-year relapse free survival of 77% for patients with, with IBC extension, as opposed to 80% for those with no extension because the survival rate is favorable. It is critical in these patients to minimize surgical complications and operative mortality, incomplete surgical resection of the thrombus is significantly associated with worse event free survival. Suggesting that sufficiently extensive surgery should, should be planned controlled, complete removal of the thrombus should be the aim of surgery and consideration should be given to avoiding radiotherapy if the thrombus is completely necrotic. So just moving on to the principles of surgery, a cavotomy and thrombus resection is indicated when there's blood flow around the thrombus. A CAV omy is indicated when there is complete cable occlusion with outflow as robust venous collateral drainage is already established. Cable replacement is not physiologically needed and I am likely to remain patent because of shunting through collaterals and the low flow through the cava route. Very few patients have lower limb symptoms. Preoperative chemotherapy increases the adherence to the IBC wall. 43% of primary surgery versus 61% with postoperative therapy. 50% and 77% in South Africa of Children receiving initial therapies of 4 to 6 weeks may still have viable therapy. Therefore, risks versus benefits of your extirpative vascular surgery must be considered careful examination of both renal vein and IVC is required during the operation. And um this may be helped with intraoperative sonar. So when we go to the types of, I'll just go on for another five minutes and then I'll be done. So when we go on to the types of operation, if you just got a level one thrombus in the renal vein, so the the you, you know, you may just need to ligate the renal vein beyond the thrombus, you may be able to resect the thrombus along with the vein or you could do thrombus extraction on block from the IVC via renal vein. Vot toy and vascular control. Whilst doing this can just be achieved with a a side biting vascular clamp. When we look at your infrahepatic, your level two IBC thrombus um below the hepatic veins. This can be removed through a vena cavotomy. And after controlling for your contralateral renal vein, your vena cava above and below the thrombus, your superior camp can be, should be placed below the hepatic confluence and this reduces the liver ischemia. And if you can remove this en block, then it's only a stage two. So now the difficult the complex operations come when we're looking at our level 33 or your suprahepatic IVC, and then that can be then divided into your infradiaphragmatic or your supradiaphragmatic. But effectively, people talk about using your liver transplantation technique with full mobilization of the liver for uh for exposure of the, the full IVC and hepatic veins. And this is otherwise known as the piggyback mobilization. However, this is not advised in a pediatric population because of the risk of lethal emolus or, or cable tears. Um Generally, these, these sort of operations will be done safer if they're on cardio pulmonary bypass. And if not, if you plan to do it, then your bypass should however be on standby if you're unable to, to achieve what you need to do or milk the thrombus down below the clamp. Um The way this the operation is described is through a circumferential dissection of the diaphragmatic central tendon around the IVC to get control of the intrapericardial IVC. And you might require either a partial or full sternotomy to do this. Um And you achieve supra dimetric intrapericardial IVC control your, your hepatic vein control with complete liver is isolation as well as below the liver and your opposite adrenal vein. Um And then the tumor thrombus is then milked down and once milked down below the level of the hepatic veins, the superior clamp has moved down and the pringle maneuver discontinued. Cavotomy is done to extract the, the Thrombus or Cect toy. If it's adherent to the wall and the IVC should be closed primarily or you may need to use a Pericardial or synthe synthetic patch. Um When we're looking at level fours and fives in the AM or the ventricle, then bi cardiopulmonary bypass will be required. Um And this may be done with deep hypothermic cardiac arrest, cooling down to 20 degrees and this helps reduce blood loss, ischemia, con hepatic congestion and the risk of embolus. Um It can be done differently. Uh You can do the abdominal and IVC dissection first and then the stot toy and your bypass of the abdominal dissection and the decision to begin with your approach, I mean, depends on, on, on the tumor itself. Otherwise, a tumor nephrectomy clearance of the IVC up to the level of the hepatic veins followed by Stoy and Atriotomy and the uh longitudinal cavotomy. Um So during your, your bypass, the tumors resected off the atrial wall and removed from the atrium and hepatic veins. Um This Atriotomy and Denno toy can primarily be repaired using a pericardial synthetic patch if resection of the right atrial wall due to due to tumor thrombus. Um I'm just going to skip a few things for the sake of time. Um Radiotherapy is required when the thrombus is resected piecemeal or there's residual viable tumor is suspected. And in, in some facilities lacking the surgical capacity to resect the IVC extension radiotherapy may be an option for local control. So just to conclude off on my last slide there, um IVC Extension must be excluded in all patients. New adjuvant chemotherapy often avoids the need for your bypass surgery and it reduces the complication rates by a half um attempt and unblock complete removal down stages it to stage two. And although it is critical to minimize surgical complications and operative mortality, sufficiently extensive surgery should be planned and lastly avoiding the radiotherapy if the thrombus is completely removed or necrotic. Ok, thank you very much. Uh uh Derek. Uh Thank you very much that is really extensive and very elaborate uh uh um explanation about these two really complex issues uh with Wilm's tumor. Um just uh just um it's quite clear that uh management of bilateral wills tumor and certainly numbers up to or just beyond the level of hepatic veins should not be carried out uh in any center uh without adequate experience and probably uh patients need to be referred to a, to a a center which has got experience in these things. My one only question is about uh the initial slides about epidemiology and the survival is better in Eastern Africa than in South Africa. Is that true? And why could that be? No? So that is so it's, it's not better there so that their survival can, it's reported in some centers that only 8% when South Africa, for example, it's 50 that last report by the SAC CSG which was published, I think in 2015, the survival in South Africa for all malignancies was 52%. So, no, it's not true. I mean, it's I might have mis I might have misread that uh slide. The survival is better in South Africa as, as compared to East Africa. Hm. Yeah, II would expect so. No. Thank you for the clarification. Um I would ask one after the other. Um uh I would ask our consultant, pediatric surgeon, Doctor Selo Mataya to make any comment or ask any questions. Sell. Hello. Are you still around? Um If Sella is not here, is Doctor Majola still around? Doctor Majola trained with us and he has been working in Port Elizabeth now. Uh Doctor Majola. Hi, Bob. Uh yes, I sit around. Thank you, Derek for that Uh Beautiful talk. Now, I don't have any questions. Uh The one that I wanted, someone just posted, uh basically, do they use any ultrasound guidance to check for the extent of the tumor intraoperatively. So, yeah. So, uh Hi Majola. Um So yes, we have. So it is, it is, it is a bit of a problem because some of our radiologists don't have that much experience, but we have had so I've done it for both bilateral worms and IVC Thrombus. Um So we have had, you know, we've had, you know, we've had cases where we've imaged prior to surgery and, and we can see the thrombus heading up to a certain level and intraoperatively when we've done the Zona, we've actually found it to be lower than what we are seeing on CT scan. And, you know, it probably could have been due to the CT scan being done two weeks prior and there's still been another cycle of chemotherapy and another week of recovery and planning for the surgery. So, we have seen that. So we have done that and then the same for the bilateral worms. We've we on one of the cases and we did the, we did the gigs um virtual rounds just a few weeks ago when one of my s presented two cases and um one of the cases of bilateral worms that was imaged with the MRI, it showed the lesions on each side just to be one at the upper pole and one at the lower pole. But actually when we went in to operate and you saw no, I mean, you could feel it as well, but when you saw no, you could confirm it was extending into the renal renal sinus. Um So yeah, we do it and I mean, the point is, you know, the point is, you know, if you're gonna do these things, it's probably best from upfront to start learning how to use this soar yourself and just doing it yourself. So you don't have to rely on radiologists coming to the theater, et cetera. OK. Uh Thank you, Derek. I see, Doctor Funeka Kolo uh is here fun trained in Johannesburg and has been working in uh which is in the Eastern Cape. Fun. Any comments, any questions for Doctor Harrison? Not sure whether fun heard me. I see Doctor Nevele Chao professor from SM uh Pretoria is here. Uh Doctor Nevele anything e can you hear me? I don't know whether the others are able to hear me. II can hear you. I just, yeah. Ok. It means they are probably busy with something. I see. Sello is still here, Sello. You want to make any comments, any questions? No, it doesn't look like. Ok. Now I'll ask uh Professor Headley uh to, to make comments or, or share his experience of many years in the past. Uh Thanks. Thanks Melander Derek. That was a, that was a very nice talk. Thanks very much. Indeed. And, and it's reassuring to know that the things that challenged me many years ago are still challenging er, surgeons today. I think um on your epidemiological uh situation and, and we all acknowledge that um children's cancer care is, is underfunded and that uh pediatric surgical cancer care is particularly uh poorly acknowledged, but we have to recognize the healthcare challenges facing uh governments throughout Sub Saharan Africa. And really children's cancer is still a very rare condition, whereas things like malaria and gastroenteritis are still overwhelming the healthcare services in many countries. And although we must keep advocating for children's cancer care, we must recognize that it is not a priority for many governments throughout the region. Um The, the or question that you raised earlier about uh whether biopsies uh preoperatively increase the stage of the disease to stage three. I mean, I think it's sorry profile. Uh I have lost you