S9630, Medroxyprogesterone in Treating Women With Breast Cancer

RATIONALE: It is not yet known whether medroxyprogesterone is effective in preventing endometrial disorder in patients with breast cancer who are taking tamoxifen. PURPOSE: Randomized phase III trial to study the effectiveness of medroxyprogesterone in preventing endometrial disorder in postmenopausal women who have ductal carcinoma in situ, lobular carcinoma in situ, Paget's disease of the nipple, stage I breast cancer, or stage II breast cancer and who are taking tamoxifen.

OBJECTIVES: * Compare endometrial pathologic diagnoses (proliferative changes, simple or cystic hyperplasia, complex adenomatous hyperplasia, hyperplasia with atypia, and carcinoma) in postmenopausal women with breast carcinoma treated with adjuvant tamoxifen who are randomly assigned to medroxyprogesterone acetate (MA) vs observation. * Compare endometrial pathologic diagnoses (persistent endometrial hyperplasia, atypia, or carcinoma) resulting in tamoxifen discontinuation and intermittent bleeding in patients treated with these regimens. * Characterize the incidence of spontaneous regression and progression of simple or cystic hyperplasia in these patients. * Characterize endometrial biopsy results using different endometrial stripe width cut-off points, for cases in which the width is at least 5 mm by endovaginal ultrasound in patients receiving tamoxifen. * Compare changes over time in endometrial oncogene expression (e.g., c-fos, c-jun, p53, IGF1) and receptor status in patients receiving tamoxifen with or without prior chemotherapy who are randomly assigned to MA vs observation. * Describe the associations among change in gene expression, receptor status, endometrial abnormality, length of tamoxifen exposure, and prior chemotherapy in these patients. OUTLINE: This is a randomized, multicenter study. Patients are stratified according to adjuvant chemotherapy (yes vs no), number of positive nodes (0-3 vs at least 4), and endovaginal sonogram endometrial stripe (less than 5 mm vs at least 5 mm). Patients are randomized to 1 of 2 arms. All patients receive adjuvant oral tamoxifen daily for five years. * Arm I: Patients undergo observation. * Arm II: Patients receive oral medroxyprogesterone acetate on days 1-14. Treatment repeats every 3 months for 5 years. Patients are followed every 6 months for 2 years and then annually thereafter. PROJECTED ACCRUAL: A total of 330 patients (165 per arm) will be accrued for this study.