Adjuvant Hormonal Therapy

For patients with lymph node involvement at radical prostatectomy, continuous hormonal therapy is considered standard care in some centers. A series of non-randomized comparisons supported the use of indefinite therapy in the form of either LHRH agonists or orchidec-tomy.113-117 More recently, a randomized trial has demonstrated benefit from long-term LHRH agonist therapy for patients with lymph node involvement delineated at radical prostatectomy (Fig. 19.4).118 This study has been criticized for low power and early termination.

Whether patients with pelvic lymph node involvement can be treated with transient adjuvant therapy instead of indefinite hormonal therapy has not been determined. Whether long-term hormonal therapy is justified in patients with other adverse pathological findings at radical prostatectomy, such as seminal vesicle involvement or extensive extracapsular disease, remains to be determined. Despite widespread use in patients with these adverse pathological findings, there is little evidence in the literature to support therapy in this setting despite high rates of early biochemical (PSA) relapse. These issues are the subject of trials currently accruing.

Within the group of 945 patients in the Radiation Therapy Oncology Group (RTOG) 85-31 trial treated with primary radiation therapy for clinically localized prostate cancer, adjuvant LHRH antagonist resulted in a 5-year disease-free survival rate of 53% compared to 20% in the arm not given adjuvant therapy.119 At a mean of 54 months follow-up, adjuvant therapy resulted in significantly improved overall survival in patients with a prostate biopsy Gleason score of 8

Figure 19.4 Kaplan-Meier estimates of overall survival based on immediate castration or observation for cases with pelvic lymph node metastases at radical prostatectomy for clinically localized prostate cancer. Vertical bars are 95% confidence intervals. The logrank test was used to calculate p values. (From Messing et al.118 with permission.)

Figure 19.4 Kaplan-Meier estimates of overall survival based on immediate castration or observation for cases with pelvic lymph node metastases at radical prostatectomy for clinically localized prostate cancer. Vertical bars are 95% confidence intervals. The logrank test was used to calculate p values. (From Messing et al.118 with permission.)

or more. Patients with better-differentiated tumors did not achieve improvement in overall survival from adjunctive hormonal therapy, although longer follow-up in other subgroups will help to determine the broader applicability of these data. For patients in the RTOG 85-31 trial with biopsy-proven pelvic lymph node involvement, continuous hormonal therapy from the time of radiation therapy resulted in better biochemical progression-free survival and absolute survival than hormonal therapy given at relapse.120 However, overall survival for the whole randomized trial did not reveal significant differences between the groups. Retrospective data from one case series suggest that continuous adjuvant antiandrogen therapy may be of benefit in patients with clinical stage T2B, Gleason score >7, and/or PSA >15 ng/ml notwithstanding the potential biases of the study design.121 The role of further short-term adjuvant hormonal therapy following radiation therapy given subsequent to NHT is to be determined.122 In one trial, which tested the utility of 6 months of adjuvant hormone after completion of NHT and radiation T, an early analysis suggested improved PSA-free survival from adjuvant therapy. However, this was not confirmed by later analysis (at 2 years).122

One criticism made of trials designed to assess the effect of combining castration and radiation therapy is that there are limited data to compare combined-modality treatment with castration alone. The British Medical Research

Council addressed this in an early trial of orchiectomy, radiation therapy alone, and or-chiectomy plus radiation therapy in patients with clinical T2-4 prostate cancer.123 The net result was that those arms that included orchiectomy had significant delay in time to clinical progression but there was no difference in overall survival or local disease control. There was a nonsignificant trend of improved survival in the radiation plus orchiectomy group (5.2 years) vs. the orchiectomy alone group (4.5 years). The trial has been criticized because of the small number of patients, the techniques and doses of radiation therapy given, and for the large proportion of patients with T2 and/or low-grade tumors. However, it does suggest potential for combined therapy that needs further examination. At this time, adjuvant hormonal therapy following radiation should be considered in patients with a high probability of early relapse as predicted by Gleason score, PSA, and stage; but more data from randomized studies are required to define the fine details of this principle. The use of long-term hormonal therapy in patients with proven lymph node involvement improves survival in both the postradical prostatectomy and postradiation therapy settings.

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