In a patient-level meta-analysis reported in The Lancet, the Early Breast Cancer Trialists’ Collaborative Group found that ovarian function suppression (OFS) with ablation or drugs was associated with reduced 15-year risk of recurrence or death irrespective of chemotherapy or tamoxifen use in premenopausal women with estrogen receptor (ER)-positive early breast cancer.
Study Details
Individual patient data were used from randomized trials comparing OFS vs no OFS in women with ER-positive or ER-unknown early breast cancer who were premenopausal at randomization and younger than 55 years of age.
Key Findings
The analysis included 18,851 women from 23 eligible trials.
Among 15,075 premenopausal patients with ER-positive or ER-unknown tumors, allocation to OFS was significantly associated with reduced recurrence rates (rate ratio [RR] = 0.82, 95% confidence interval [CI] = 0.77–0.87, P < .00001); larger reductions in risk were observed in patients with confirmed premenopausal status after chemotherapy (or who did not receive chemotherapy) than among those with unconfirmed premenopausal status after chemotherapy (heterogeneity P = .0004).
Among confirmed premenopausal women, recurrence reductions were larger in patients in older trials without tamoxifen (RR = 0.61, 95% CI = 0.52–0.71, P < .0001) than in more recent trials of OFS plus tamoxifen vs tamoxifen (RR = 0.79, 95% CI = 0.70–0.91, P = .0008). In these more recent trials, the additional reduction in recurrence with OFS appeared to be greater in women aged younger than 45 years (RR = 0.73, 95% CI = 0.63–0.86) vs those aged 45 to 54 years (RR = 0.95, 95% CI = 0.75–1.21, P = .072). Among patients younger than 45 years, risk of breast cancer mortality was similarly reduced (RR = 0.74, 95% CI = 0.58–0.94, P = .012).
No increase in deaths without recurrence was observed. Findings did not differ significantly by OFS method or other recorded patient or tumor characteristics.
The investigators concluded: “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.”
The corresponding entity for The Lancet article is The Early Breast Cancer Trialists’ Collaborative Group, Clinical Trial Service Unit, Nuffield Department of Population Health, Oxford, UK.
DISCLOSURE: The study was funded by the Nuffield Department of Population Health, University of Oxford; Cancer Research UK; the Breast Cancer Research Foundation; and the UK Medical Research Council. For full disclosures of the study authors, visit thelancet.com.
