SAN ANTONIO — The digital rectal exam continues to play a critical role in identifying men with prostate cancer, according to a poster presentation by Joel Slaton, M.D., and Cesar Ercole, M.D., at the annual meeting of the American Urological Association.
Twenty-seven of 85 men (32%) with low prostate-specific antigen (PSA) levels and an abnormal digital rectal examination (DRE) had positive biopsies, reported Dr. Slaton and Dr. Ercole of the University of Minnesota, Minneapolis. Of those, 9 men (33%) were found to have high-grade tumors. The cancers would have been missed if the screening had relied on PSA alone.
The investigators attributed the false-negative PSA findings to tumors that were so poorly differentiated they underproduced PSA.
The study was a retrospective review of 3,817 prostate cancer screening visits between 1990 and 2000 where both DRE and PSA were performed. Of those, 81% of men had both a normal DRE and a normal PSA (defined as less than 4 ng/L). Those men did not undergo biopsy.
The remaining 719 men all had an abnormal DRE, a high PSA, or both, and all underwent biopsy; 240 of them (33%) were found to have cancer.
Of the 359 men with high PSA and abnormal DRE, 139 (39%) had positive biopsies, and slightly more than 20% had high-grade tumors. Of the 275 men with high PSA and normal DRE, 74 (27%) had positive biopsies, and about 20% had high-grade tumors.