Combination therapy of ethinylestradiol and somatostatin analogue reintroduces objective clinical responses and decreases chromogranin a in patients with androgen ablation refractory prostate cancer

Purpose: We evaluated whether a combination therapy of ethinylestradiol and somatostatin analogue can reintroduce objective clinical responses in patients with metastatic androgen ablation refractory prostate cancer (PC). Materials and Methods: Ten patients with stage D3 disease and bone metastases who had progression despite initial responses to combined androgen blockade and in whom antiandrogen withdrawal subsequently failed discontinued combined androgen blockade and received 1 mg ethinylestradiol orally daily and 73.9 mg lanreotide acetate intramuscularly every 4 weeks. Serum prostate specific antigen (PSA), chromogranin A (CgA), Eastern Cooperative Oncology Group performance status and bone pain scores were assessed at regular intervals. Median followup was 18 months (range 10 to 24). Results: Nine of the 10 cases (90%, 95% CI 55.5 to 99.8) had an objective clinical response, defined as a greater than 50% PSA decrease (median 87.1%, range 50.2% to 94.4%). PSA normalization (less than 4 ng/ml) was achieved in 3 cases. All patients reported significant and durable improvement in bone pain (median duration 17.5 months) and performance status (median duration 18 months) without major treatment related side effects. Two patients with disease progression died secondary to PC at 16 and 10 months, respectively. All other patients were without progression. We observed a statistically significant decrease in serum CgA during administration and at the response to therapy (median 38.4%, range 28.6% to 64.9%, (p < 0.0001). Interestingly CgA was not increased at relapse. Conclusions: This combination therapy seems to reintroduce an objective clinical response and symptomatic improvement in androgen ablation refractory PC cases