Screening for prostate cancer: an analysis of the early experience

Several common misconceptions have fueled the debate over the early detection and treatment of prostate cancer. While prostate cancer is often described as a common cancer that older men die with rather than of, the reality is that the incidence, mortality, and mean age and stage at diagnosis of prostate cancer are very similar to those of breast cancer, which is rarely the subject of similar concerns. Many studies have confirmed that given enough time, all clinically detected prostate cancers will inexorably progress locally and eventually metastasize to regional lymph nodes as well as to distant sites. The relatively slow doubling time compared to that of other cancers and the wide spectrum of biologic activity of prostate cancer have made retrospective studies reporting the long-term survival of conservatively treated patients highly suspect due to selection bias and inadequate follow-up. While it is accepted that a large number of men harbor clinically insignificant cancers in their prostate glands, these estimates have been based on careful pathologic step-sectioning studies of prostates obtained either at autopsy or after cystoprostatectomy for bladder cancer. Several studies have now demonstrated that currently available diagnostic modalities for detecting prostate cancer, DRE, PSA, and TRUS, are not able to detect a significant proportion of small, clinically unimportant cancers. Rather, studies have shown that while the traditional DRE has been largely unsuccessful in detecting prostate cancers at a sufficiently early stage for effective treatment with either radical prostatectomy or radiation therapy, a combination of the DRE and PSA followed by TRUS and ultrasound-guided biopsy in those with abnormal results can detect an increased proportion of clinically significant prostate cancers while they are still confined to the prostate gland and thus more likely to be eradicated by treatment. Several randomized trials are now under way in this country and in Europe that may settle many of these issues over the next decade. However, currently available data suggest that prostate cancer screening holds the promise of decreasing the considerable morbidity and mortality caused by this disease.