Cancerous changes in the prostate can cause an elevation in the PSA (prostate-specific antigen) level even within the normal range. A steadily rising PSA over time can be indicative of a prostate cancer, and it allows for the detection of potential malignancy in men who have what are conventionally considered normal PSA levels.

Decreased PSA with age: As men get older, their PSA level tends to slowly rise, whether cancer is present or not, which is a normal aging process. It does not decrease.

No change in PSA level: Though it's possible that PSA may not rise in some cases of prostate cancer, the majority of cases would show a rise in PSA levels.

A decrease in PSA levels: Decreased levels of PSA suggest that cancer or other conditions affecting the prostate such as benign prostatic hypertrophy, certain infections, or inflammation are either not present or are decreasing in severity.