Age-related differences in persistence in women with breast cancer treated with tamoxifen or aromatase inhibitors in Germany

Abstract

Aims: To study age-related persistence in postmenopausal women with endocrine-responsive breast cancer treated with tamoxifen (TAM) and aromatase inhibitors (AI).

Methods: Data on 29,245 patients diagnosed with metastatic or non-metastatic breast cancer (BC) and initially treated with TAM or AI between 2004 and 2013 were included. The primary outcome measure was the age-dependent rate of discontinuation of endocrine treatment within 5years after initiation. Discontinuation of therapy was defined as a period of at least 90days without treatment. A multivariate Cox regression model was created to determine the influence of age on the risk of discontinuation. Health insurance type (private/statutory), type of care (gynecological/general), region (West/East Germany), concomitant diagnoses (depression, osteoporosis, and diabetes), and Charlson Comorbidity Score were included as covariates.

Results: The mean ages of the women in the <70 and ≥70 groups were 55.9 (SD: 9.7) and 77.4 (SD: 5.4) years, respectively. Within 5years after treatment initiation, 88.8% of women <70 of age and 82% of women ≥70 years of age had terminated treatment (p-value<0.001). Patients aged ≥70 exhibited a lower risk of treatment discontinuation than patients aged <70 (HR=0.75, 95% CI: 0.66-0.85). Furthermore, gynecological practices, disease management programs, and high Charlson scores increased persistence.

Conclusions: Overall, the present study indicates that persistence rates are low in both women with BC aged <70 and those aged ≥70 years. We also found that younger women with BC are at a higher risk of treatment discontinuation than older women.

Keywords: Aromatase inhibitors; Breast cancer; Persistence; Tamoxifen.