Vietnamese and Chinese women with hormone receptor-positive operable breast cancer benefit from adjuvant treatment with surgical oophorectomy and tamoxifen.

In premenopausal women with operable breast cancer not selected for estrogen receptor status or with estrogen receptor-positive tumors, 5- and 10-year DFS and OS rates are significantly improved following adjuvant oophorectomy and tamoxifen.

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The hypothesized benefit of adjuvant luteal phase oophorectomy was not shown in this large trial.

552 Background: Reports of randomized trials evaluating adjuvant ovarian suppression or ablation with and without tamoxifen are limited in number, useful comparative data and long-term follow-up. Methods: From 1993–99 we recruited 709 Vietnamese and Chinese premenopausal women with clinical stage II-III operable breast cancer to a multi-site randomized prospective clinical trial of immediate pre-mastectomy adjuvant surgical oophorectomy followed by tamoxifen for 5 years (n=356) or mastectomy alone with the same combined hormonal therapy on recurrence of disease (n=353).The primary study endpoints were disease-free and overall survival.This report provides analyses for an extended follow-up period after 5 years. Results: With a median follow up of 7 years, disease-free and overall survival were significantly better with adjuvant therapy (log-rank p-values of 0.0003 and 0.0002). Ten year DFS probabilities of 62% and 51% (95%CI 4–22%), and OS probabilities of 70% and 52% (95% CI 6–34%) between adjuvant and observation groups were observed. In the estrogen receptor positive patient subset, 5 and 10 year DFS probabilities were 83% and 61%, and 66% and 47%; and 5 and 10 year OS probabilities were 88% and 74% and 82% and 74% in adjuvant and observation groups respectively. Conclusions: In women with estrogen receptor positive operable breast cancers, 5 and 10 year disease free and overall survival rates following adjuvant oophorectomy and tamoxifen compare favorably with those from other adjuvant regimens. In estrogen receptor positive patients, the hazard function with adjuvant therapy increases after year six. No significant financial relationships to disclose.