Early discontinuation to adjuvant endocrine therapy in the ECOG-ACRIN TAILORx Trial.

Abstract

7004 Background: The TAILORx study demonstrated women with an intermediate Oncotype DX score receive the same benefit with endocrine therapy (ET) compared to chemoendocrine therapy (CET). However, early discontinuation of adjuvant ET is problematic among breast cancer survivors, with previous studies suggesting that up to 50% of women do not adhere to the full 5 years of recommended ET treatment. The aim of this study was to identify patient-level risk factors associated with early discontinuation of ET in the TAILORx study. Methods: TAILORx was coordinated by the ECOG-ACRIN Cancer Research Group. Participants were a subgroup of 954 women who completed additional measures on health-related quality of life (HRQoL) including endocrine symptoms (ES) physical well-being (PWB) and social well-being (SWB) prior to initiating ET, which categorized into three groups by tertile for analysis. All participants were diagnosed with hormone-receptor–positive, human epidermal growth factor receptor 2–negative, axillary node–negative breast cancer who started ET within a year of study entry. Early discontinuation of ET, defined as discontinuation less than 4 years from initiation for reasons other than death or recurrence, was assessed by clinician report. Rate of discontinuation was calculated using Kaplan-Meier estimates, and Cox-proportional hazards joint models were used to analyze the association between rates of adherence to ET with patient-level factors. Results: In a joint model, receipt of CET therapy (vs receipt of ET only; HR = .59, 95% CI .38-.94, p = .02) and age above 40 (versus age < = 40; HR = .30, 95% CI .14-.66, p = .003) were associated with a lower probability of early discontinuation of ET. Adjusted for these factors, a history of depression compared to no history of depression (HR 1.82, 95% CI 1.19-2.77, p = 0.005), worse ES compared to better ES (HR 1.70, 95% CI 1.06-2.74, p = 0.03), worse PWB compared to better PWB (HR 2.12, 95% CI 1.30-3.45,p = 0.003), and worse SWB compared to better SWB (HR 1.94, 95% CI 1.20-3.13, p = 0.007) were individually and significantly associated with a higher probability of early discontinuation of ET, although none reached statistical significance when all were included in a joint model. Conclusions: Younger women are at risk for early discontinuation and modifiable characteristics such as HRQoL and history of depression are potential risk factors for early discontinuation of ET. These results support systematic screening for HRQoL and depressive symptoms to identify women at risk for discontinuation of ET. Clinical trial information: NCT00310180 .