May 31, 1998
In a study of prostate cancer at different ages, Johns Hopkins researchers have found that at diagnosis, older men have more extensive disease than younger men even if their prostate specific antigen (PSA) levels are the same. PSA is a protein made by the prostate; rising blood levels suggest that the prostate is enlarged or even cancerous.
"The finding shows that both doctors and older men must be especially vigilant," says H. Ballentine Carter, M.D., associate professor of urology. "The blood test results don't necessarily mean the same level of disease when ages differ," he said. The study, presented May 31 at the annual meeting of the American Urological Association in San Diego, Calif., was done with cancers that could not be detected by digital rectal exams.
The results are a new wrinkle on a long-standing problem over deciding whether to do further testing on men with raised PSA levels, Carter says. "Lowering the PSA threshold means you pick up more small, harmless tumors. Raising the PSA threshold means you're more likely to miss life-threatening tumors. The present study gives us age as an additional guide in deciding when it might be worthwhile to do further testing in men with non-palpable prostate cancer. At any particular PSA level, a key factor in catching cancer when it is still curable is the man's age."
The Hopkins team studied 492 men who had undergone surgery to remove their prostates. The men were divided into three age groups (40-50, n=69; 51-60, n=227; 61-73, n=196) and five pre-treatment PSA categories: (2.5-4.0, n=36; 4.1-6.0, n=100; 6.1-8.0, n=122; 8.1-10.0, n=76; >10.0, n=135). Patients were considered curable if the cancer was either confined to the prostate or had not spread outside the gland to lymph nodes and the seminal vesicles.
For a given PSA range, increasing age was associated with lower probability of cure. If a man 40 to 50 years old had a PSA level of 4.0, for example, he had an 89 percent chance of having curable cancer; but a man with the same PSA level who was 61 to 73 years old had only a 78 percent chance of having a curable cancer. For PSA levels of 8.1 to 10, the rates of curable cancer were 73 percent for men ages 40 to 50 and 49 percent for men ages 61 to 73.
Other authors of the study include Jonathan I. Epstein, Patrick C. Walsh and Alan W. Partin.