Hormonal therapy prolongs survival in irradiated locally advanced breast cancer: a European Organization for Research and Treatment of Cancer Randomized Phase III Trial.

PURPOSE To assess the long-term contribution of adjuvant chemotherapy (CT) and hormonal therapy (HT) in patients with locally advanced breast cancer, and to evaluate the impact of time of analysis on the results during accrual and up to 8 years after closure of a randomized phase III trial. MATERIALS AND METHODS In a trial using a factorial design, 410 patients were randomized between radiotherapy (RT) alone, RT plus CT, RT plus HT, and RT plus HT plus CT. RESULTS CT and HT each produced a significant prolongation of the time to locoregional tumor recurrence and to distant progression of disease, with the combined treatments providing the greatest therapeutic effect. At the time of trial closure, a significant improvement of survival was observed in patients who received CT (P = .004); however, with a longer follow-up duration, this effect disappeared (P > .05). HT did not initially appear to improve survival (P = .16); however, in the latest analysis with a long-term follow-up duration, a significant improvement of survival was seen (P = .02). A consistent 25% reduction in the death hazards ratio has been seen at all evaluations since trial closure in patients who received HT. The best survival results were observed in patients who received RT, HT, and CT (P = .02), with a reduction of 35% in the death hazards ratio. CONCLUSION An improvement in survival attributable to HT has been shown in patients with locally advanced breast cancer. The greatest therapeutic effect was seen in the treatment group that received both CT and HT. The improvement obtained with HT became apparent only after long-term follow-up evaluation.