Persistence in patients with breast cancer treated with tamoxifen or aromatase inhibitors: a retrospective database analysis.

Compliance and persistence are often underestimated in breast cancer (BC) treatment. The aim of our study was to analyze the persistence with tamoxifen (TAM) and aromatase inhibitors (AI) in postmenopausal women with hormone-receptor-positive BC and to identify determinants of non-persistence. We used data of the Disease Analyzer database (IMS HEALTH, Germany) including 2,067 general practices and 397 gynecological practices. Out of a dataset of 15 million patients, we identified BC patients with a first-time TAM or AI prescriptions from October 2001 to December 2010. For persistence analyses, 12,412 women on tamoxifen, 2,796 on anastrozole, 647 on exemestane, and 1,657 on letrozole met the inclusion/exclusion criteria. Within 3 years of follow-up, the discontinuation rates increased to 52.2 % for tamoxifen, 47 % for anastrozole, 55.1 % for exemestane, and 44.3 % for letrozole treated women. A minor proportion of patients switched to a different endocrine treatment; 33 % tamoxifen, 20 % anastrozole, 22.9 % exemestane, and 23 % letrozole. The multivariate hazard ratios of the cox regression models showed that patients younger than 50 were most likely to discontinue initial therapy when compared with the reference group of women over 70 (p < 0.001). In contrast, patients treated in gynecologist practice had significantly longer persistence than patients who obtained their prescriptions in general practitioner practice (p < 0.001). In addition, the presence of the co morbidities like diabetes (p < 0.001) or depression (p < 0.002) was also associated with decreased risk of treatment discontinuation. Persistence with all endocrine treatments in women with hormone-receptor-positive BC is low and needs to be significantly increased to improved outcome in clinical practice. Further research is required to understand this complex issue.