Masuda N, Iwata H, Rai Y et al.
Osaka National Hospital, Osaka, Japan.
Breast Cancer Res Treat 2011;126:443–51.
Editor’s note: While not necessarily of huge scientific importance, this article provides some reassurance and help with regard to a practical question that arises on a weekly basis in the treatment of premenopausal women with early stage breast cancer. The use of 3-monthly (10.8 mg) injections of goserelin in premenopausal women would of course be much more convenient than the monthly (3.6 mg) form, but the former are only licensed for the treatment of prostate cancer. While both dose levels of goserelin are sustained-release formulations, the polymer in which they are prepared is slightly different in the higher dose to allow for gradual release of goserelin compared with the monthly formulation. In the past, studies of goserelin at a dose of 10.8 mg have suggested 20% lower area under the curve (AUC) values than the monthly injection. While such constraints are unlikely to greatly influence our recommendations, the equivalence of monthly and 3-monthly injections in such patients has not been demonstrated thus far, and in terms of a study with clinical outcomes, a non-inferiority study is extremely unlikely since there is no overwhelming motivation either in academia or in the pharmaceutical industry. In this respect, the current study provides a reasonable level of reassurance that the monthly and 3-monthly subcutaneous injections are similar, at least in terms of estradiol suppression.