PROGNOSTIC IMPLICATIONS OF PROSTATE-SPECIFIC ANTIGEN IN PATIENTS WITHLOCALLY ADVANCED PROSTATE-CANCER TREATED WITH HIGH-ENERGY NEUTRON BEAM THERAPY - PRELIMINARY-RESULTS

Serial serum prostate-specific antigen (PSA) levels were analyzed retr ospectively for prognostic implications in 70 patients with locoregion al (Stages B2, C, and Dl) prostate cancer who were managed with high e nergy neutron beam therapy. Three groups of patients were identified. Group I included 30 patients whose serum PSA level decreased to the re ference range (0-4 ng/mL) following neutron therapy and remained so su bsequently: 28 (93 %) remained disease-free and 2 (7 %) have failed di stantly. All 30 patients (100 %) had no evidence of locally progressiv e disease. This group was categorized as having a good prognosis. The mean time for serum PSA value to decline to reference range was six mo nths; calculated mean time to achieve a stable baseline PSA was 53 +/- 3 7 days. Follow -up period ranged from twelve to fifty-six months (m edian: 21 months). Group II consisted of 13 patients in whom there was an initial decrease in serum PSA to reference range followed by a sub sequent increase: 6 of 13 (46 %) have no overt clinical progression of disease; 7 (54 %) have either persistent locoregional or distant meta static disease. Follow-up period was from twelve to seventy-two months (median: 39 months). Calculated mean time to achieve stable baseline PSA for serum PSA in this group was 61 +/- 21 days. Group III patients had a persistently elevated or rising serum PSA concentration. Of 27 patients in this group, only 9 (33 %) have no evidence of disease prog ression, while 18 patients (67 %) have failed already, either locoregi onally or distantly. Follow-up period ranged from twelve to sixty-nine months (median: 21 months). Mean time to achieve stable baseline of s erum PSA in this cohort of patients with a poor prognosis was 108 +/- 76 days. We conclude that PSA has a predictable prognostic value in pa tients with locally advanced prostate cancer managed with high energy neutron beam therapy. Rapid normalization of PSA after therapy indicat es a good prognosis. Persistent elevation signifies either presence of persistent locoregional disease or development of distant metastases. Subsequent elevation of the serum PSA concentration after definitive therapy signals progression of prostate cancer.