Join Drs Leila Aval, Kalp Patel, Dan Coulson and Alice fortune for a critical appraisal of RCTs (with a focus on patient-reported outcome measures/ PROMs) crash course along with an emergency A-E scenario. You will be sent an abstract for appraising prior to the session and then the tutors will go through it in depth during the session. These sessions are tailored for the SFP interviews, specifically for London and Oxbridge deaneries.
Abstract to appraise before the session
Summary
This summary presents an analysis of the risk of lung carcinoma in the men and women of the National Institutes of Health–AARP cohort. In this study, researchers compared incidence rates and hazard ratios adjusted for potential confounders between men and women across strata of smoking use. Findings suggest that women are not more susceptible than men to the carcinogenic effects of cigarette smoking in the lung, yet further research should confirm the higher incidence rates for never smoking women as opposed to never smoking men. Join this interactive session to gain further insight about the NIH-AARP cohort and the risk of lung carcinoma in men and women.
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Learning objectives
Learning Objectives:
- Understand the current scientific literature about cigarette smoking and lung carcinoma risk.
- Identify the differences between incidences and mortailities in men and women related to cigarette smoking.
- Learn the methodology used to compare relative and absolute risks of smoking and lung cancer in men and women.
- Evaluate the hazards and risk factors associated with lung cancer.
- Analyze the National Institutes of Health (NIH)-AARP case study to gain a better understanding of the findings relating to lung cancer in men and women.
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NIH Public Access Author Manuscript Lancet Oncol. Author manuscript; available in PMC 2009 July 1. I Published in final edited form as: - Lancet Oncol. 2008 July ; 9(7): 649–656. doi:10.1016/S1470-2045(08)70154-2. P A u h Cigarette smoking and the subsequent risk of lung carcinoma in r M the men and women of a large prospective cohort study a u Neal D. Freedman, PhD , Michael F. Leitzmann, MD , Albert R. Hollenbeck, PhD , Arthur c Schatzkin, MD 2,4, and Christian C. Abnet, PhD 2 p t 1 Cancer Prevention Fellowship Program, Office of the Director, National Cancer Institute, NIH, DHHS, Bethesda, MD, USA 2 Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Rockville, MD, USA 3 AARP, Washington, DC, USA N 4 Senior investigator H P Summary A u Background—Whether women are more susceptible than men to lung cancer caused by cigarette h smoking has been controversial. We aimed to determine the susceptibility of men and women to r cigarette smoking by comparing lung carcinoma incidence rates by stratum of smoking use in the M men and women of the National Institutes of Health–AARP cohort. a u Methods—The analysis included 279,214 men and 184,623 women from eight U.S. states aged 50 c to 71 years at study baseline who were mailed a questionnaire between October 13, 1995 and May i 6, 1996 and were followed until December 31, 2003. We present age-standardized incidence rates t and multivariate adjusted hazard ratios (HR) adjusted for potential confounders, each with 95% confidence intervals (CI). Findings—Duringfollow-up,lungcarcinomasoccurredin4,097menand2,237women.Incidence rateswere20.3per100,000person-years(95%CI:16.3–24.3)inneversmokingmen(99carcinomas) and 25.3, 95% CI: 21.3–29.3 in never smoking women (152 carcinomas); for this group, the HR for lung carcinoma was 1.3 (95%CI: 1.0–1.8) for women relative to men. Smoking was associated with N increased lung carcinoma risk in both men and women. The incidence rate of current smokers of >2 H packs per day was 1,259.2 (95%CI: 1,035.0–1,483.3) in men and 1,308.9 (95%CI: 924.2–1,693.6) P in women. Among current smokers, in a model adjusted for typical smoking dose, the HR was 0.9 A (95%CI: 0.8–0.9) for women relative to men. For former smokers, in a model adjusted for years of A cessation and typical smoking dose, the HR was 0.9 (95%CI: 0.9–1.0) for women relative to men. h o M a Corresponding author: Neal Freedman, PhD, MPH, Cancer Prevention Fellow, Nutritional Epidemiology Branch, Division of Cancer u Epidemiology and Genetics, 6120 Executive Blvd, EPS/320, MSC 7232, Rockville, MD 20852 USA, V: +1 301 594-6119, F: +1 301 s 496-6829, freedmanne@mail.nih.gov. i Contributors t All authors contributed to the designing of the study, the interpretation of the data, the drafting of the manuscript, and approved the final version of the report. AS obtained funding for the study, ML, AH, and AS acquired the data, and ND, ML, and CA analyzed the data. Conflicts of interest The authors declare no conflicts of interest. Publisher'sDisclaimer:ThisisaPDFfileofanuneditedmanuscriptthathasbeenacceptedforpublication.Asaservicetoourcustomers proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Freedman et al. Page 2 Incidence rates of adenocarcinoma, small cell, and undifferentiated tumors were similar in men and women; incidence rates of squamous tumors in men were twice that in women. I Interpretation—Our study suggests that women are not more susceptible than men to the - carcinogenic effects of cigarette smoking in the lung. Future studies should confirm whether P incidence rates are indeed higher in never smoking women than in never smoking men. A u h Introduction r Lungcanceristheleadingcauseofcancerrelatedmortalityworldwide,withalmost1.2million M 1 2 a deaths per year and an estimated 162,000 deaths per year in United States. u 3,4 c Cigarette smoking is estimated to cause 85–90% of lung cancers in the United States. p 1orldwide, lung cancer incidence and mortality is three times higher in men than in women. t In the United States, there are estimated to be 114,690 incident lung cancers (90,810 deaths) in men and 100,330 incident lung cancers (71,030 deaths) in women in 2008. Whether men and women have different susceptibilities to the carcinogens in cigarette smoke with respect to lung cancer remains the focus of considerable controversy, with authors debating the merits ofusingabsoluterisks(incidenceormortalityratesinsmokers)orrelativerisksduetosmoking tomakethiscomparison. 5–9 Fewstudieshavepresentedbothabsoluterisksandrelativerisks. Some, but not all, case-control and cohort studies have suggested that smoking causes a N significantly larger relative increase in lung cancer risk in women than in men.13 H Whereas, results from cohort studies generally find similar incidence and mortality rates in P 5,14 A men and women with comparable smoking histories. A t Typically, incidence rates of lung cancer in never smoking men and women serve as the o denominator for relative risk calculations. Though lung 3ancer in never smokers is responsible M foranestimated15,000deathsperyearintheUnitedStates, mostepidemiologicstudieshave a limited case numbers in this important group. A recent report analyzed incidence data from 6 n large cohort studies. These data suggest higher incidence rates in never smoking women s (five studies) than never smoking men (four studies).15 But, the largest study of men had r less than 50 cancers and only three studies included both men and women.4,15 These t incidence rates are in contrast to those published for mortality, where rates for never smoking men were significantly higher than for never smoking women in most studies including two very large American Cancer Society cohorts with 621 cancers in never smoking men and 1582 cancers in never smoking women. To address this controversy, we took advantage of the large size of the National Institutes of N Health (NIH)-AARP cohort to compare absolute and relative risks of smoking and lung H carcinomainmenandwomen.Wepresentage-standardizedincidenceratesoflungcarcinoma - by categories of cigarette use and use multivariate Cox proportional hazard models that A estimate the relative increase in lung carcinoma risk due to cigarette smoking. Furthermore, A we directly estimate the hazard ratio of lung carcinoma in women compared with men within u stratums of cigarette use. h r M Methods n The NIH-AARP Diet and Health study is a large prospective cohort designed to study the u association of diet and environmental risk factors and cancer risk. It has been described c previously.16 Between October 13, 1995 and May 6, 1996, a risk factor questionnaire was p mailed to 3.5 million members of AARP aged 50–71 years who resided in eight US states t (California, Florida, Georgia, Louisiana, Michigan, New Jersey, North Carolina, and Pennsylvania). AARP was formerly known as the American Association of Retired Persons and is a US organization whose membership is open to those at least 50 years of age. Of the Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 3 617,119 persons (17.6% of 3.5 million) who returned the questionnaire, 566,402 respondents filledoutthesurveyinsatisfactorydetailandconsentedtobeinthestudy.Weexcludedsubjects N with cancer or death at baseline (51,217), proxy respondents (15,760), those with total energy H intake more than twice the interquartile range (4,419), and those with incomplete information - A about cigarette use (18,806), or cigar and pipe use (12,363). The resulting cohort included A 463,837 participants: 279,214 men and 184,623 women. The conduct of the NIH-AARP Diet u and Health Study was reviewed and approved by the Special Studies Institutional Review h Board of the U.S. National Cancer Institute (NCI). r M Cohort follow-up n As described previously, 17 addresses for members of the NIH-AARP cohort were updated u annually by matching the cohort database to that of the National Change of Address database c maintained by the U.S. Postal Service, specific changes of address requests from participants, p t updated addresses returned during yearly mailings, and the Maximum Change of Address database (Anchor Computer). We ascertained vital status by annual linkage of the cohort to the Social Security Administration Death Master File, cancer registry linkage, questionnaire responses, and responses to other mailings. Identification of lung carcinomas Incident cancers were identified by linkage between the NIH-AARP cohort membership and I 11 state cancer registry databases (8 states from baseline together with Arizona, Nevada, and - A Texas). We17stimate that approximately 90% of cancers will be detected in the cohort by this A approach. Cancer sites were identified by anatomic18ite and histologic code of the u International Classification of Disease for Oncology. All primary incident cancers of the h bronchus and lung (ICD 34.0 – ICD 34.9) were considered for the present analysis. By r histologic code, lung carcinomas included small cell (8002, 8041, 8042, 8044, and 8045), M adenocarcinoma (bronchoalveolar: 8250 and 8251 and other: 8140, 8200, 8231, 8260, 8290, n 8310, 8323, 8430, 8480, 8481, 8490, and 8550), squamous (8050, 8070, 8071, 8072, 8073, u and 8074), undifferentiated/large cell (8012, 8020, 8021, 8022, 8031, and 8032), and other or c not otherwise specified carcinoma (8010, 8011, 8046, 8123, 8560, and 8562). p t Exposure Assessment The baseline questionnaire asked about demographics, alcohol intake, tobacco smoking, physical activity, and included a food frequency questionnaire of 124 items. Questionnaires for smoking have shown high reproducibility (r=0.94) and validity (r=0.92 for women and r=0.90 for men relative to serum cotinine levels).9,20 Participants were asked if they had smoked more than 100 cigarettes during their life (ever cigarette smokers), smoking intensity I (cigarettes smoked per day), whether they were currently smoking, and years since smoking H P cessationforformersmokers.Thosewhoreportedquittingwithinthepastyearwereconsidered A current smokers. To maintain adequate numbers in each stratum for analyses stratified by u histologic type, we used a summary variable for cigarette smoking use (never smokers, former h smokers of ≤ 1 pack per day, former smokers > 1 pack per day, current smokers of ≤ 1 pack r per day, and current smokers > 1 pack per day). Participants were also asked if they had ever M smoked pipes or cigars regularly for a year or longer. a u Typical alcohol, fruit, vegetable, red meat, processed meat, and total energy intake were c calculated from the questionnaire, taking account of frequency and serving size and including p individual and mixed foods as described previously. 21–23 t Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 4 Statistical Methods N Analyses were performed with SAS version 9.1. A significance level of less than 0.05 was H used and all tests were two-sided. - A Follow-up time from the date the questionnaire was returned (beginning October 25, 1995) to A diagnosis of lung cancer, date of death, or end of follow-up (December 31, 2003), or the date u moved out of registry ascertainment area was used as the underlying time metric. Age- h standardized incidence rates and 95% confidence intervals were calculated with five year age r M bands and sex-specific rates standardized to the entire NIH-AARP Diet and Health study n population. u c Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional p hazards regression. Except where noted, all models were adjust2d for categorical variables of t alcohol intake and education tabulated in Table 1, BMI in kg/m (<18.5, 18.5–<25, 25–<30, 30–35, and ≥35), usual physical activity throughout the day (sit all day, sit much of the day, stand/walk often/no lifting, lift/carry light loads, and carry heavy loads), vigorous physical activity (never, rarely, 1–3 times/month, 1–2 times/week, 3–4 times/week, 5 or more times per week),andcontinuousmeasuresforageatcohortentryandintakesoffruit,redmeat,processed meat, vegetables, and total energy. For the less than 3% of the cohort that was missing data for a particular covariate, a separate indicator variable for missing was included in the models. I - We tested the proportional hazards assumption by modeling interaction terms of time and A cigaretteuseandfoundnostatisticallysignificantdeviations.Usingageastheunderlyingtime A metric did not alter results. Ending follow-up time at the first cancer diagnosis (regardless of u site) reduced case numbers slightly, but did not appreciably affect the results. We excluded the h first two years of follow-up and the results did not change and are not reported. r M Assuming a causal relation between cigarette smoking and lung carcinoma, we calculated n u multivariate adjusted population a24ributable risk percents using the delta method as c implemented by Spiegelman et al. p t Results Menandwomenhadsimilarages,whereaswomenhadlowerdailyenergy(kcal)intake,higher intake of fruit and vegetables per 1000 kcal/day, less formal education, drank less alcohol, and were less likely to ever smoke cigarettes, pipes, or cigars than men. In contrast, a higher percentage of women 31,542 (17.1% of 184,623) were current smokers then were men 35,256 (12.6% of 279,214) (Table 1). Between October 25, 1995 and December 31, 2003, during I 3,334,956 years of follow-up, 6,334 study participants were diagnosed with lung carcinoma H (4,097 men and 2,237 women). P A Inneversmokersofcigarettes,theage-standardizedincidencerates(per100,000person-years) u for lung carcinoma were 22.8 (95% confidence interval (CI): 19.0–26.7) for men and 25.4 h (95%CI:21.4–29.5)forwomen(datanotintables).But,afterexcludingeversmokersofpipes r or cigars from this category, the age-standardized incidence rates became 20.3 (95%CI: 16.3– M 24.3) for men and 25.3 (95%CI: 21.3–29.3) for women (Table 2). From an age adjusted Cox a u proportional hazards model, women who did not smoke cigarettes, pipes, or cigars had a HR c of 1.2 (95% CI: 1.0–1.6) relative to men in this group (data not in tables). After multivariate p adjustment for potential confounders, the risk estimate became 1.3 (95%CI: 1.0–1.8). t Table 2 presents incidence rates for lung carcinoma in cigarette smokers, tabulated by years ofcessationandtypicaldose,alongwithmultivariateadjustedhazardratiosdirectlycomparing lung carcinoma risk in women with that for men of the same smoking stratum. Age-adjusted Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 5 hazard ratios were similar to those with multivariate adjustment (data not shown). Current smokersof>40cigarettes(>2packsperday),hadincidenceratesof1,259.2(95%CI:1,035.0– N 1,483.3, 139 carcinomas) in men and 1,308.9 (95% CI: 924.2–1,693.6, 48 carcinomas) in H women. Among this group, women had a HR of 1.1 (95% CI: 0.8–1.6) relative to men. - A Incidence rates were higher in male current smokers of less than 2 packs of cigarettes per day A thaninfemalesmokersinthesamesmokingstratum.Asanexample,women(535carcinomas) u who reported currently smoking 11–20 cigarettes per day had a HR of 0.8 (95% CI: 0.7–0.9) h relative to men (605 carcinomas) in this same smoking stratum. For current smokers overall, r incidence rates standardized by age and typical smoking dose were 667.4 (95% CI: 635.0– M 699.9) in men and 584.8 (95%CI: 550.9–618.7) in women (data not in table). After adjusting n for typical smoking dose, the HR for currently smoking women relative to currently smoking u men was 0.9 (95%CI: 0.8–0.9; data not in table). c p For former smokers compared within stratum of time since quitting and usual dose while t smoking, men tended to have higher incidence rates than women, but these differences were not statistically significant. As an example, women that reported smoking > 40 cigarettes (>2 packs per day) but stopped smoking more than 10 years ago (51 carcinomas) had a RR of 0.8 (0.6–1.1)relativetomen(337carcinomas)inthisgroup.Forformersmokersoverall,incidence rates standardized by age, years of cessation, and typical smoking dose were 191.7 (95% CI: 183.7–199.7) in men and 185.6 (95% CI: 172.2–198.9) in women (data not in table). From the I corresponding Cox proportional hazards model, women had a HR for lung carcinoma of 0.9 - (95% CI: 0.9–1.0) relative to men (data not in table). A A We also calculated incidence rates standardized by age and all stratums of cigarette use along u with pipe or cigar use. After standardization by age and smoking use, incidence rates were h 196.3 (95% CI: 190.1–202.5) in men and 190.6 (95% CI: 172.2–209.0) in women. In the r corresponding Cox proportional hazards model, women had a HR of 0.9 (95% CI: 0.8–0.9) M relative to men for lung carcinoma. We estimate that ever smoking cigarettes, pipes, or cigars n accounted for 87% (95% CI, 85–89) of lung carcinoma in men and 85% (95% CI, 82–87) of u lung carcinoma in women in this cohort. c p Among lung carcinomas with known histologic sub-type (5,126 of 6,334 carcinomas), t adenocarcinomas were the most frequent sub-type in never smokers (165 of 206, 80%), ever- smokers (2,562 of 4,920, 52%), men (1,574 of 3,321, 47%), and women (988 of 1,805, 55%). (Table 3) The hazard ratios associated with smoking varied by histologic type. For example, relative to never smokers, we found higher hazard ratios associated with currently smoking > 1 pack per day for squamous tumors (men: 128.2, 95% CI: 60.1–273.6, 219 carcinomas; women: 139.8, 95% CI: 56.0–349.1, 70 carcinomas) then for adenocarcinomas (men: 17.6 I (95%CI:13.2–23.5,238carcinomas;women:16.4,95%CI:12.7–21.1).Foradenocarcinomas, H never smoking women had borderline increased risk relative to never smoking men (HR for P sex, 1.4, 95%CI: 1.0–2.0). The age-standardized incidence rate of adenocarcinoma in never A smokers was 12.8 (95% CI: 9.6–16.0) in men and 17.0 (95% CI: 13.7–20.3) in women; among u smokers, incidence rates were similar in men and women. h r Wefoundnosignificantdifferencesbetweenmenandwomenbycigarettesmokinghistoryfor M undifferentiated and small cell carcinomas. Incidence rates for squamous tumors were twice a as high in men as in women for each stratum of cigarette use. u c Discussion p t In this large prospective study, we found slightly higher age-standardized incidence rates of lungcarcinomainneversmokingwomenthaninneversmokingmen.But,amongeversmokers of comparable amounts of cigarettes, we observed slightly lower incidence rates in women Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 6 relative to men. Adenocarcinomas were the most common histological type in both sexes. Among never smokers, incidence rates of adenocarcinoma were higher in women than men, but similar for small cell, squamous, and undifferentiated tumors. In smokers, incidence rates I - for squamous tumors were twice as high in men as in women, but did not differ for P adenocarcinomas, small cell, or undifferentiated tumors. A u In this cohort of participants aged 50–79 years, incidence rates per 100,000 person-years for h lung carcinoma in never smokers were 20.3 (95% CI: 16.3–24.3; 99 carcinomas) in men and r 25.3 (95% CI: 21.3–29.3; 152 carcinomas) in women. Incidence rates of lung cancer per M 100,000 person-years in never smokers aged 40–79 years were recently published from six a cohorts.15 The incidence rates for women (data from 5 cohorts) were 14.4 (95% CI: 8.2–23.6; u 37 cancers) in the Swedish Uppsala/Orebro Lung Cancer Register cohort (U/OLCR), 15.2 c (95%CI: 9.1–24.5; 168 cancers) in the Nurses Health Study, 19.3 (95%CI: 14.2–27.5; 15 p cancers) in the First National Health & Nutrition Examination Survey Epidemiologic Follow- t Up study (NHEFS), 20.7 (95%CI: 13.5–31.1; 142 cancers) in the Multiethnic cohort (MEC), and 20.8 (95%CI: 13.5–31.2; 91 cancers) in the California Teachers Study (CTS). Rates in men (four cohorts) were 4.8 (95% CI: 2.2–10.6; 10 cancers) in the U/OLCR, 11.2 (95%CI: 6.5–19.0; 43 cancers) in the Health Professionals Follow-Up study, 12.7 (95%CI: 10.2–18.2; 4 cancers) in the NHEFS, and 13.7 (95% CI: 9.0–21.5; 47 cancers) in the MEC. Case numbers inthosestudiesweresmall,particularlyformen.Nevertheless,theseresultstogetherwiththose N of our study suggest that never smoking women may be at significantly increased risk of lung H carcinoma relative to never smoking men. In contrast, previous studies have suggested that P lung cancer mortality rates are higher in never smoking men than never smoking women. 3 A Differences in lung cancer survival,25,26 in men and women might explain these differences A between studies of incidence and mortality. t o Among ever-smokers (6,083 carcinomas), we found similar age-standardized incidence rates M inmenandwomenwithcomparablecigarettesmokinghistories,thoughincidenceratestended a to be slightly higher in men than women in the same category, especially among current n s smokers. Data from five incidence an5,14ree mortality studies with substantially smaller case r numbers (ranging from 141 to 2,948) are consistent with these findings. Some, but not all, t previous studies have reported that the relative increase in risk associated with smoking is greater in women than men. 8,10–13 We found that smoking increased risk by a similar magnitude in both men and women. It is not clear why results have differed between studies, though most previous studies had small numbers of cancers in never smokers. Our study benefited from a large sample size and a large number of cancers, which provided stable estimates of lung carcinoma incidence rates in never smokers and allowed us to explore individual histologic subtypes. Alternatively, the largest difference between men and women N has been reported for the squamous and small cell histological types.0,13 Changing H prevalence of histologic types over time7–29 may also explain study heterogeneity. - A We observed similar age-standardized incidence rates for adenocarcinoma, small cell, and A u undifferentiated tumors in men and women. In contrast, the incidence rates for squamous h tumorsinmenwerealmosttwicethatinwomenandthiswastrueforallcategoriesofsmoking, r includingneversmoking.SimilarresultswereobservedinUSSEERdata,wheretheincidence M rate of squamous tumors were higher in men than in women, and the incidence rates of n adenocarcinomas,smallcell,andundifferentiatedtumorsweremoresimilarbetweenthesexes. u 27–29 Increased numbers of squamous cancers in men could reflect physiological differences, c or differences in inhalation depth or cigarette composition including the use of filters, nicotine p content, and type of tobacco used.0–34 We did not ascertain cigarette brand preference or t inhalation depth. Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 7 Our comparison of the incidence of smoking and lung cancer by sex is unlikely to be significantly affected by differential recall of smoking practices in men and women, because N previous studies comparing self-reported smoking use and biochemical markers for smoking H reported comparable accuracy of assessment in male and female US Caucasians 19,35 who - A constitute 93% (424,776 of 458,725) of our cohort. A The strengths of this study include the large size of the cohort and 6,334 incident carcinomas u h which is substantially larger than previously published studies. The large size provided stable r estimates for rates of lung carcinoma among never smokers and allowed us to stratify by M histologic type. Cancers were ascertained prospectively allowing the determination of both n incidence rates by cigarette smoking stratum and the relative risks associated with cigarette u use. Men and women received the same questionnaire, allowing direct comparison within the c same study population. We also adjusted our estimates for pipe and cigar use. p t This study was limited by the lack of information on the age of smoking initiation at baseline, precludingusfromcalculatingsmokingdurationandpack-years.Inasubsetofthecohortwho returned a follow-up questionnaire in September 2004 (118,557 men and 72,030 women), the median age at smoking initiation was slightly younger in men (17 years, interquartile range: 13–22) than in women (17 years, interquartile range: 17–22). Age at cessation did not vary by age of initiation. This data suggests that within the same stratum of cessation and typical dose, menmayhaveslightlygreatercumulativecigaretteexposurethanwomen,perhapscontributing I to slightly higher incidence rates in former and current smoking men relative to women - A observedinthisstudy.Inaddition,welackedassessmentofexposuretoenvironmentaltobacco A smoke. u h Among never smokers, differences in the exposure to environmental tobacco smoke by men r and women could lead to different incidence rates in never smoking women and men in this M andotherstudies.Serumcotininelevels,awellvalidatedbiochemicalmarkeroftobaccosmoke n exposure, were slightly higher in men than women among never smokers in the nationally u representative US National Health Interview Survey. 36,37 Therefore, environmental tobacco c smoke likely does not explain the higher incidence rates of lung carcinoma in never smoking p women than in never smoking men in this study. Furthermore, though environmental tobacco t smoke has strong public health significance, the lung cancer risk conferred by ever cigarette smoking in this and other studies is nearly ten times the estimated risk for environmental tobacco smoke. 38–40 Thus, we predict that differences in environmental tobacco smoke exposure would not meaningfully affect the incidence rates observed in each stratum of cigarette use, nor would they confound our estimates of the association between cigarette use and lung carcinoma risk by sex. I In addition, smoking was assessed at a single time-point. Participants may have changed their H P smoking use over time, which could affect lung cancer risk. We also lacked data on inhalation A depth and cigarette type. Finally, participants in our cohort were more educated, l16s likely to u becurrentsmokers,andmorelikelytobenon-HispanicWhitethantheUSpopulation, which h may limit generalizability to other subpopulations. r M In summary, we found that among participants who reported never smoking tobacco in any a form, women had slightly higher rates of lung carcinoma than men. But, when we compared u smokers with similar smoking histories we found that men tended to have slightly higher c incidenceratesthanwomen.Ourstudysuggeststhatwomenarenotmoresusceptiblethanmen p to the carcinogenic effects of cigarette smoking in the lung. Vigorous efforts should continue t to be directed at eliminating smoking in both sexes. Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 8 Acknowledgements N Cancer incidence data from Arizona was collected by the Arizona Cancer Registry; from Georgia by the Georgia H Section; from Michigan by the Michigan Cancer Surveillance Program; from Florida by the Florida Cancer Dataillance P System under contract to the Department of Health (DOH); from Louisiana by the Louisiana Tumor Registry; from A NevadabytheNevadaCentralCancerregistry;fromNewJerseybytheNewJerseyStateCancerRegistry;fromNorth A Carolina by the North Carolina Central Cancer Registry; from Pennsylvania by the Division of Health Statistics and t Research, Pennsylvania Department of Health; from Texas by the Texas Cancer Registry. The views expressed herein o are solely those of the authors and do not necessarily reflect those of the Cancer registries or contractors. The r Pennsylvania Department of Health specifically disclaims responsibility for any analyses, interpretations or M conclusions. We are indebted to the participants in the NIH-AARP Diet and Health Study for their outstanding n cooperation. u c Cancer Epidemiology and Genetics (Bethesda, MD, USA). The funding organization had no role in the study design, p collection of data, analysis and interpretation of data, in the writing of the report, or in the decision to submit the paper t forpublication.Allauthorshadfullaccesstothedataandfinalresponsibilityforthedecisiontosubmitforpublication. References 1. Parkin DM, Bray F, Ferlay J, Pisani P. Global cancer statistics, 2002. CA Cancer J Clin 2005;55:74– 108. [PubMed: 15761078] N 2. Jemal A, Siegel R, Ward E, et al. Cancer statistics, 2008. CA Cancer J Clin 2008;58:71–96. [PubMed: H 18287387] P 3. Thun MJ, Henley SJ, Burns D, Jemal A, Shanks TG, Calle EE. Lung cancer death rates in lifelong A nonsmokers. J Natl Cancer Inst 2006;98:691–9. [PubMed: 16705123] A 4. U.S. Department of Health and Human Services. 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Characteristic* Men Women N H P Participants, No. 279,214 184,623 A Lung carcinomas, No. 4,097 2,237 u h Age at entry into the cohort (Age; Median, IQR) 62.7 (57.8–66.7) 62.3 (57.5–66.4) o Alcohol intake, No. (%) r 0 drinks/day 57,204 (20.6) 53,571 (29.1) M > 0 – 1 drinks/day 139,299 (50.0) 106,435 (57.9) a > 1 – 3 drinks/day 51,760 (18.6) 18,963 (10.3) u > 3 drinks/day 30,160 (10.8) 5,007 (2.7) s r Body Mass Index (Median, IQR) 26.6 (24.4–29.4) 25.7 (22.9–29.5) p Education, No. (%) t Less than high school 15,938 (5.9) 11,154 (6.2) 12 years (completed high school) 43,336 (15.9) 46,938 (26.2) Some post-high school training 88,324 (32.4) 65,871 (36.8) Completed college 60,551 (22.2) 27,325 (15.3) Completed graduate school 64,255 (23.6) 27,748 (15.5) Ethnicity, No. (%) Non-Hispanic white 259,140 (93.7) 165,636 (90.9) Non-Hispanic black 7,407 (2.7) 10,215 (5.6) N Hispanic 5,238 (1.9) 3,478 (1.9) H Asian/Pacific Islander/Native American 4,720 (1.7) 2,891 (1.6) - A Fruit intake (Servings per 1000 kcal/day; Median, IQR) 1.3 (0.8–2.1) 1.7 (1.0–2.5) Vegetable intake (Servings per 1000 kcal/day; Median, IQR) 1.9 (1.4–2.5) 2.2 (1.6–3.1) A t Total daily energy intake (kcal; Median, IQR) 1,866 (1,434–2,415) 1,458 (1,119–1,888) o r Cigarette Smoking Status, No. (%) M Never 83,577 (29.9) 81,414 (44.1) a Current 135,256 (12.6) 31,542 (17.1) u s Usual number of cigarettes smoked (current and former), No. (%) r ≤ 1 packs/day 101,388 (51.8) 72,147 (69.9) p > 1– 2 packs/day 70,778 (36.2) 25,882 (25.1) t > 2 packs/day 23,471 (12.0) 5,180 (5.0) Stopped 10 or more yearsing (Among former smokers), No. (%) 127,767 (79.7) 50,311 (70.2) Stopped 5–9 years 21,048 (13.1) 13,106 (18.3) Stopped 1–4 years 11,566 (7.2) 8,250 (11.5) Smoked pipes or cigars regularly for a year or longer? No. (%) No 198,793 (71.2) 183,848 (99.6) N Yes 80,421 (28.8) 775 (0.4) H - *Categories may not add up to 463,837 participants because of missing data. P A A t h r M a n s c p t Lancet Oncol. Author manuscript; available in PMC 2009 July 1. Freedman et al. Page 12 d n h a t m a 5 e j o e ( ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) d a r i r . 2 . . . . . . . . . . . . . . . . . . . . s † f e e ) – – – – – – – – – – – – – – – – – – – – – – c a t m a C 1 . 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r N r r t g 3 ( 1 1 0 1 8 1 8 0 0 6 8 7 9 8 7 7 8 8 0 1 e H i d i i 1 6 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 0 0 1 1 a - u z l o i P M h r s a A m A d u , t d I k h s C n r j % 3 ) ) ) 8 6 ) 7 0. . . 0 . . . . . . . . . e M a ( f . 2 5 9 . .3 8 2 2 2 2 2 1 2 3 3 1 2 3 5 6 b †e s ( – 3 4 5 – – 7 – 3. . . – . . . . . . . . . e a i t 0 1 ( ( ( 56 7 ( 7 1 1 10 5 1 1 1 1 1 1 2 3 3 e u a r 1 2 . . . 8 9( . 7 0 5 8 0 6 4 2 5 4 5 2 7 3 , s t r 9 1 4 7 8 9 5 9 5 9 5 8 4 8 1 1 3 . .5 0 7 a c u z 1 1 1 1 1 2 2 1 2 2 4 4 i i Mha i t f e t I ) ) i * 50 C 7 ) 0 5 3 ) 7 6 3 0 0 9 3 5 5 7 5 6 8 36 o z / % 5 . . . 8..7 3 4 . 3 7 7 6 8 0 6 7 1 4 5 . 2 6 o d t 9 – 2 9 5 1 – – – 1 – – – – – – – – – – – – – –, a e a r s . . – . . . . .9 . . . . . . . . . . . . . . . y m n c a 6 2 ( 3 8 4 6 7 9 9 8 6 3 3 9 4 7 7 1 6 0 2 2 d o s e - ( 3 . 2 1 ( ( ( 7 ( ( ( ( ( ( ( ( ( ( ( ( ( ( t N W e c o 8 5 2 2 9 00 9 6 9 8 8 5 2 8 . . 3 6 8 2 9 2 8 u I A i r 1 2 4 01 1 2 2 1 2 3 4 3 2 3 4 5 51 3 6 6 1 30 h H p 1 1 u P r A t . i A e . 7 t u s o , 5 1 6 7 9 6 5 3 7 7 5 29 2 7 5 3 1 3 3 4 4 4 a h y N 2 1 1 2 5 2 1 u o a u r m t M o i a i r 7 c r. n r y 5 5 2 4 4 7 0 9 9 9 6 6 7 8 8 8 6 0 5 2 l i u c n 8 , 5 , , 5, , , , , , , 04 , , , 5 6 , , , , 14 i i c g s , 5 4 1 1 5 2 2 2 3 1 1 8 1 2 1 6 3 6 9 3 1 4 y e r u e 1 p e p l P u ws t n o at 2 a i i l s d ) , e a u t C i d T e j % ) ) ) ) ) . ) 1 . . .7 1 . . . . . . . . . c s e a 9 ) . . . . . 61 . 7 2 2 3 7 2 3 3 4 2 3 4 5 71 d d a † s r – – – – – 2 – – 7 0 6 – 5 6 2 7 3 6 7 8 2 . , a i a t 0 1 1 3 6 5. 0 3 9 .3 6. 6 5 9 . .6 6 4 8 . .2 i e at r r r 1 6 0 7 8 ( ( 0 0 ( ( ( 6 ( ( ( ( ( ( ( ( ( e i a N f i d 1 2 4 7 49 2 6 3 77 0 9 0 0 5 9 5 0 0 5 2 4 r s t s u z 1 1 1 2 2 1 2 2 2 3 2 3 3 4 5 f a u H a M h d y m - r h o a P t e t d A i m o s A e ) ) s o d u n * 5 C ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) . 3 r o - h e e / 9 3 7 6 . 0 1 1. . 7 4 8 9 5 8 0 . 7 2 2 1 0 , h i g o f i e 5 2 4 3 9 0 1 2 3 8 3 4 5 74 3 5 6 8 , 5 7 9 , – c r g r n a r s . 3 6 4 – . . . 9 . . . . . . . . – . . . – . 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Page 14 n a t e c 5 e u o e ( d d w i r . s †a f e g ) – c t i m a C 0 r N r a t c ( e H i d i i 0 a - l a a o i P M a r m a A h s m A d u , t ) k h t C n r u ) e M d 5 9 b †a ( – e a t i . e u r a ( , s v d 8 a c l a 1 i i u a i t M h f e t i I o *d51 C ) o i s 5 8 a n r a ( – y e d e r 7 d o a n e ( t N W - d n . u I g c s 3 h H A i e u P p r A t i A t u o 8 a h N 1 u o u r t M i a r c n e 8 l u n , i c s 5 y r e p p P u t o i ) , t C i u . c d 5 3 d †a ( – . , t i . i e r r ( e i N v d . r s l a 5 f a H u a d y - Mh h o P e t r A t m o i A d s o s u 5 I s r o r h *d 1 C ) n h i e o i s 5 5 a c r s r r a ( – t P n a M n d e sr 0 a A t i a e a n e ( r A e e n M - d n . s t a d u g c s 6 e e f s s A i e e e d d r p e t s a p s t d i t g i s a l z e t o 9 s r o u N 5 e h d m d b e a o a n e t C d . i e r s s N h d ) d e 3 e i y C e - - 2 n s d l t a o 2 e c a v i g r 1 r a u t g i P f r a i n o ; c s c l s l c a e t i r g e f t w d t l n o a e a y e e i c e i e / n y n 5 u o t t e c d i d d a a a t a p n o i a c o i g c 1 c t r o o a l i n e e i d a e d t o r o c h t d p a i m u m d a e z e a H S C s I r g a t r C F * A † H i F Lancet Oncol. 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