Breast cancer chemoprevention: little progress in practice?

1018 www.thelancet.com Vol 383 March 22, 2014 In The Lancet, Jack Cuzick and colleagues report the fi rst results from IBIS-II (International Breast cancer Intervention Study II), in which 3864 postmenopausal women at high risk of breast cancer were randomly assigned to receive the potent, non-steroidal aromatase inhibitor anastrozole or placebo every day for 5 years. After a median follow-up of 5 years, 40 (2%) of 1920 women in the anastrozole group and 85 (4%) of 1944 in the placebo group had developed breast cancer (hazard ratio 0·47, 95% CI 0·32–0·68). This fi nding is in keeping with those of other similar studies. So far, unsurprisingly, the investigators have not recorded evidence for a diff erence in breast cancer or allcause mortality: 18 deaths had been reported in the anastrozole group and 17 in the placebo group. The design of IBIS-II was essentially pragmatic: women enrolled were at increased risk of breast cancer, whether because of family history or previous diagnosis of noninvasive lesions (eg, ductal carcinoma in situ, lobular carcinoma in situ, and atypical ductal hyperplasia). The predicted cumulative incidence of all breast cancers after 7 years in the control group (5·6%) refl ects an increased risk in the participants, and is in line with other similar studies of breast cancer prevention. All the women in IBIS-II had a mammogram and physical breast examination at baseline, unless these procedures had been done within 12 months of enrolment, and then at least every 2 years during the treatment period. 78 (62%) of 125 cancers were detected through screening. At the end of the 5 years, follow-up was as per local practice (including imaging), with no central review of imaging from either before or during the study, or of the lesions (invasive or otherwise) diagnosed before or during the trial. The issue with studies of pharmacological breast cancer prevention is whether there is true prevention of clinically signifi cant, life-threatening breast cancers, early treatment of tumours overdiagnosed by intrinsic Breast cancer chemoprevention: little progress in practice? united voice. We must not miss this unique opportunity to make the strongest possible case for tuberculosis, push it up the political agenda, and secure global commitment and leadership that will steer a new path to end tuberculosis forever.