Patient-level meta-analysis of effects of ovarian ablation or suppression on breast cancer recurrence and survival

Fro premenopausal women with ER-positive early breast cancer, the additional protective effect of ovarian function suppression (OFS, by ablation or drugs) may depend on menopausal status after any chemotherapy, and tamoxifen ussage. An Early Breast Cancer Trialists’ Collaborative Group patient-level meta-analysis of 15,075 premenopausal women, younger than 55 years, with ER-positive or ER-unknown breast tumors in 23 randomized trials compared outcomes after OFS versus no OFS. Allocation to OFS significantly reduced recurrence rates (RR 0.82; p<0.00001), with larger reductions in women who were confirmed premenopausal after chemotherapy (or who did not receive chemotherapy) than in those with unconfirmed premenopausal status after chemotherapy. Among confirmed premenopausal women, recurrence reductions were larger in older trials without tamoxifen (RR 61; p<0.0001) than in more recent trial of OFS plus tamoxifen versus tamoxifen (RR 0.79; p=0.0008). In these more recent trials, the additional recurrence reduction with OFS appeared larger in women younger than 45 years than in women aged 45-54 years (RR 0.73 versus RR 0.95; p=0.072); in those younger than 45 years, breast cancer mortality was similarly improved (RR 0.74; p=0.012). There was no increase in deaths without recurrence. Findings did not differ significantly by OFS method or other recorded patient or tumor characteristics. The authors conclude that for premenopausal women with ER-positive early breast cancer, even if chemotherapy or tamoxifen are given, OFS significantly reduces the 15-year risk of recurrence and death.