Barbara Pistilli, MD, Institut Gustave Roussy, Villejuif, France, discusses non-adherence to endocrine therapy when treating breast cancer. Using the prospective multicenter CANTO cohort, non-adherence to tamoxifen was assessed in premenopausal women 3 years after prescription. After the first year non-adherence was 1 in 6 but sharply increased to 1 in 3 by the third year. Dr Pistilli emphasises the need for an intervention programme to reduce non-adherence. This interview was recorded via an online conference call with The Video Journal of Oncology (VJOncology).