OVARIAN ABLATION IN EARLY BREAST-CANCER - OVERVIEW OF THE RANDOMIZED TRIALS

Background Among women with early breast cancer, the effects of ovaria n ablation on recurrence and death have been assessed by several rando mised trials that now have long follow-up. In this report, the Early B reast Cancer Trialists' Collaborative Group present their third 5-year ly systematic overview (meta-analysis), now with 15 years' follow-up. Methods in 1995, information was sought on each patient in any randomi sed trial of ovarian ablation or suppression versus control that began before 1990. Data were obtained for 12 of the 13 studies that assesse d ovarian ablation by irradiation or surgery, all of which began befor e 1980, but not for the four studies that assessed ovarian suppression by drugs, all of which began after 1985. Menopausal status was not co nsistently defined across trials; therefore, the main analyses are lim ited to women aged under 50 (rather than ''premenopausal'') when rando mised. Oestrogen receptors were measured only in the trials of ablatio n plus cytotoxic chemotherapy versus the same chemotherapy alone. Find ings Among 2102 women aged under 50 when randomised, most of whom woul d have been premenopausal at diagnosis, 1130 deaths and an additional 153 recurrences were reported. 15-year survival was highly significant ly improved among those allocated ovarian ablation (52 . 4 vs 46 . 1%, 6 . 3 [SD 2 . 3] fewer deaths per 100 women, logrank 2p=0 . 001), as was recurrence-free survival (45 . 0 vs 39 . 0%, 2p=0 . 0007). The num bers of events were too small for any subgroup analyses to be reliable . The benefit was, however, significant both for those with (''node po sitive'') and for those without (''node negative'') axillary spread wh en diagnosed. In the trials of ablation plus cytotoxic chemotherapy ve rsus the same chemotherapy alone, the benefit appeared smaller (even f or women with oestrogen receptors detected on the primary tumour) than in the trials of ablation in the absence of chemotherapy (where the o bserved survival improvements were about six per 100 node-negative wom en and 12 per 100 node-positive women). Among 1354 women aged 50 or ov er when randomised, most of whom would have been perimenopausal or pos tmenopausal, there was only a non-significant improvement in survival and recurrence-free survival. Interpretation In women aged under 50 wi th early breast cancer, ablation of functioning ovaries significantly improves long-term survival, at least in the absence of chemotherapy. Further randomised evidence is needed on the additional effects of ova rian ablation in the presence of other adjuvant treatments, and to ass ess the relevance of hormone-receptor measurements.