Diagnostic Value of Molecular Forms of Prostate-Specific Antigen for Female Breast Cancer

Objectives: To examine the diagnostic value of prostate-specific antigen (PSA) subfractions in the serum of female breast cancer patients. Design and Methods: PSA subfractions (free PSA, F-PSA; PSA bound to α1-antichymotrypsin, PSA-ACT) were determined in the serum of patients with breast cancer and in the serum of healthy women. Serum was injected into a high-performance liquid chromatography column and all fractions were analyzed for PSA using a highly sensitive PSA immunofluorometric assay. We studied 3 normal male sera, 3 sera from prostate cancer patients who underwent radical prostatectomy (all for comparative purposes), 3 sera from healthy women, 3 sera from women with breast cancer obtained presurgically, and 7 sera from women with breast cancer, postsurgically. Results: All male sera contained mostly PSA-ACT complexes and very little free PSA. Sera from all healthy women also contained mostly PSA-ACT complexes and nondetectable or traces of free PSA. All 3 presurgical sera from patients with breast cancer contained predominantly free PSA. Patients who had surgical resection of the breast tumor and were in remission had postsurgical serum PSA subfractions similar to those of healthy women (i.e., mostly PSA-ACT complexes). Conclusion: The serum PSA subfractions of breast cancer patients are substantially different from serum PSA subfractions of male patients, healthy females, and females who have apparently been treated successfully for breast cancer. These findings may form the basis for a serological diagnostic test for breast cancer