Prostate-specific-antigen (PSA) screening for prostate cancer remains controversial because no randomized trials have shown that early detection and aggressive treatment of prostate cancer can reduce deaths from the disease. With the advent of PSA screening, the lifetime risk of a diagnosis of prostate cancer is now about 16 percent, whereas the lifetime risk of death from prostate cancer is about 3.4 percent. Obviously, most prostate cancers that are diagnosed in the United States are not destined to be fatal, notes Michael J. Barry, M.D., of Harvard Medical School, in a recent commentary.
Dr. Barry points out that PSA screening guidelines vary and that the optimal screening strategy remains unknown. On the basis of available data, men who are 50 to 75 years of age (depending on risk factors and general health) should be made aware of the availability of the PSA test and its potential harms and benefits so that they can make an informed choice about screening, recommends Dr. Barry. His research was supported in part by the Agency for Healthcare Research and Quality (HS08397).
As Dr. Barry notes, the sensitivity and specificity of the PSA test and the threshold at which a result should prompt a biopsy are unclear. Men with suspicious findings on digital rectal exam and a PSA level of 4.0 ng per ml (upper limit of normal) or less have a probability of cancer of at least 10 percent, and a transrectal biopsy is usually recommended. The optimal number and pattern of biopsy specimens and number of times biopsies should be repeated are now hotly debated. Also, the specificity of the PSA test is suboptimal, and as a result, about 75 percent of men who undergo a prostate biopsy because they have PSA levels of 4-10 ng per ml do not have cancer. Finally, the optimal treatment of identified prostate cancers is controversial. Standard treatments, including radical prostatectomy, external-beam radiation therapy, and brachytherapy, are associated with serious side effects such as sexual dysfunction and incontinence.
More details are in "Prostate-specific-antigen testing for early diagnosis of prostate cancer," by Dr. Barry, in the May 3, 2001 New England Journal of Medicine 344(18), pp. 1373-1377.