Evaluation of adjuvant estramustine phosphate, cyclophosphamide, and observation only for node-positive patients following radical prostatectomy and definitive irradiation. Investigators of the National Prostate Cancer Project.

In 1978 the National Prostate Cancer Project launched two protocols evaluating adjuvant therapy following surgery (Protocol 900) or irradiation (Protocol 1,000) for clinically localized prostate cancer. All patients underwent staging pelvic lymphadenectomy. Following definitive treatment, patients were randomized to either cyclophosphamide 1 gram/m2-IV every 3 weeks for 2 years, estramustine phosphate 600 mg/m2-po daily for up to 2 years, or to observation only. Patient accession closed in 1985 and includes 184 to Protocol 900 (170 evaluable) and 253 to Protocol 1,000 (233 evaluable). Lymph node involvement was identified in 198 patients (49% of total), 29% in Protocol 900, 63% in Protocol 1,000. Median progression-free survival (PFS) for patients with nodal involvement in Protocol 1,000 receiving estramustine phosphate adjuvant was longer (37.3 mo) compared to cyclophosphamide (30.9 mo) and to no treatment (20.9 mo). Median PFS for patients with limited nodal disease in Protocol 1,000 was longer (39.9 mo), regardless of adjuvant, compared to extensive nodal disease (20.7 mo). However for patients with extensive nodal involvement, those receiving adjuvant estramustine phosphate experienced a significantly longer median PFS (32.8 mo) compared to adjuvant cyclophosphamide (22.7 mo) and no adjuvant (12.9 mo). We conclude that adjuvant estramustine phosphate is of benefit in prostate cancer patients with extensive pelvic node involvement receiving irradiation as definitive treatment.