Yet another study has questioned the benefit of prostate cancer screening with the prostate-specific antigen (PSA) test, in this case for men who have low PSA values at their initial test. European researchers reported Monday that, for men with the lowest PSA values, repeat testing, biopsies and cancer treatment reduce quality of life but do little to increase survival. They found that among men with PSA levels lower than 2 nanograms per milliliter in their first test (4.0 or lower is usually considered normal), 24,642 men would have to be screened and 724 cases of prostate cancer would have to be treated to save one life. In contrast, for men with first levels between 10 and 19.9 mg/nl, 133 men would need to be screened and 60 treated to prevent one death. The study did not examine men with higher PSA levels because there is general agreement that such men need futher testing.
Prostate cancer is the most common form of cancer -- other than skin cancer -- to be diagnosed in U.S. men and the second leading cause of cancer death, behind only lung cancer, according to the American Cancer Society. About 217,730 men will be diagnosed with the tumors this year, and more than 32,000 will die. A man has about a 15.8% lifetime chance of being diagnosed with prostate cancer but only a 2.8% risk of dying from it. The disparity in the numbers arises not because treatment is highly successful but because the majority of prostate cancers are slow-growing tumors that pose little risk to the man who has them. In fact, autopsy studies show that most elderly men have undiagnosed prostate tumors when they die. The problem is that physicians have no accurate way to differentiate between those tumors that are slow-growing and present little or no risk and those that are aggressive and need treatment. Some groups have advocated that the cutoff PSA value for further screening be lowered to 2.5 mg/nl, but critics charge that this would double the number of men who undergo unnecessary biopsies.