Beneficial effect of combination hormonal therapy administered prior and following external beam radiation therapy in localized prostate cancer

Abstract

Purpose : The aim of the present study isto investigate whether combined androgen blockade associated with radiation therapy for localized prostate cancer decreases at 12 and 24 months the rate of ppsitive follow-up biopsies and serum PSA compared to radiation therapy alone. This is the report of an interim analysis. Methods and Materials : One hundred and twenty patients with clinical Stage B1-T2a, B2-T2b/T2c, and C-T3/ T4, adenocarcinoma of the prostate were entered in a prospective randomized study. After written informed consent, the subjects were randomly allocated between external beam radiation therapy (EBRT) alone (group 1), 3 months of neoadjuvant combination therapy (LHRH-agnist + Flutamide) prior to EBRT (group 2), and a third group receiving combination therapy 3 months before, during, and 6 months after EBRT. There is no significant difference between the three groups concerning age, stage of disease, grade of tumor, and pretreatment PSA levels. Control transrectal ultrasound (TRUS)-guided needle biopsies (one core was taken from the initial cancer site regardlss of the presence or absence of TRUS abnormalities) were done 12 and 24 months after the end of EBRT. Serum PSA measurements were done on schedule visits. Results : Ninety-two and 68 patients underwent biopsies at 12 and 2 months, respectively, after the end of radiation therapy. While 62% of control patients at 12 months in Group 1 discloed residual neoplasm, only 30 and 4% showed residual disease in groups 2 and 3, respectively ( p = 0.0005). When looking at 24 months, 65, 28, and 5% showed residual cancer for groups 1, 2, and 3, respectively ( p = 0.00001). The PSA measurements indicate also at 12 months a difference between the three groups ( p < 0.0001), except at 24 monts, the difference between the group 2 and 3 is no longer significant. Conclusion : The preliminary analysis of this clinical trial indicates that patients treated with radiation therapy alone show a significantly higher rate of positive biopsies at 12 and 24 months after the end of radiation therapy as compared with those treated with total antiandrogen blockade (TAB) and radiation therapy. When analyzing the median PSA serum levels, we found the same advantage at 12 mnths, but, at the time of the analysis at 24 months, the PSA levels are not different between groups 2 and 3.