Adjuvant endocrine therapy with tamoxifen in young women with breast cancer: determinants of interruptions vary over time.

BACKGROUND: In premenopausal women with hormone receptor-positive breast cancer (BC), 5 years of tamoxifen is recommended. Little is known about reasons for interruption in this population. The aim was to estimate the incidence of tamoxifen interruption and its correlates among younger women. PATIENTS AND METHODS: Using a prospective cohort Elippse 40 of women with BC aged ≤ 40 diagnosed between 2005 and 2008, we studied 196 women. Tamoxifen interruption was defined as two or more consecutive months without dispensed prescription of tamoxifen, based on pharmacy refill database. Two periods were studied: between tamoxifen initiation and 16 months after BC diagnosis, and between 16 and 28 months.
RESULTS: Among women treated with tamoxifen, 42% interrupted within the first 2 years of treatment. During the first period, treatment interruptions were associated with a lack of understandable information about endocrine treatment and insufficient social support. During the second period, another set of factors were associated with interruption: treatment side-effects, no longer fearing cancer relapse, lack of social support, no opportunity to ask questions at the time of diagnosis, and fewer treatment modalities.
CONCLUSIONS: Improving information and patient-provider relationship might prevent interruption. Particular attention should be paid to women with little social support.