Margaret A.WinkerMD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Senior EditorIndividualAuthor
In Reply.—Increasing the PSA threshold to 5 or 6 ng/mL, as Dr Parker suggests, misses 30% to 50% of prostate cancers and decreases the proportion of curable cancers detected, thus defeating the purpose of screening. The cost of free PSA testing in only 9% of screened men (with PSA level of 4-10 ng/mL and with a benign prostate examination) is low compared with the 20% biopsy savings.
Dr Peven comments that the free PSA test "only increases the yield of carcinoma by 3%." Free PSA does not increase sensitivity. Rather, as shown in his Table 1, it increases specificity (avoids 20% of unnecessary biopsies) with minimal loss of sensitivity (detects 95% of cancers). In his theoretical population of 400 men, 60 would be spared unnecessary biopsies and 5 patients with cancer would be missed. Peven questions using free PSA testing to avoid biopsies, since 8% of patients whose free PSA test results are negative have cancer. This is only slightly higher than the prevalence in the general population (4%). Although all men could undergo a biopsy, this approach would be an inefficient use of resources because 92% of the biopsies in men with more than 25% free PSA would be negative. The cancers that would be detected would be primarily in older men with less aggressive tumors.
Catalona WJ, Southwick PC. Free PSA for Detecting Prostate Cancer—Reply. JAMA. 1998;280(21):1825. doi:10-1001/pubs.JAMA-ISSN-0098-7484-280-21-jbk1202