Adjuvant endocrine therapy non-initiation and non-persistence in young women with early-stage breast cancer

Purpose: Characterizing oral adjuvant endocrine therapy (ET) non-initiation and non-persistence in young women with breast cancer can inform strategies to improve overall adherence in this population. Methods: We identified 693 women with hormone receptor-positive, stage I–III breast cancer enrolled in a cohort of women diagnosed with breast cancer at age ≤ 40 years. Women were classified as non-initiators if they did not report taking ET in the 18 months after diagnosis. Women who initiated but did not report taking ET subsequently (through 5-year post-diagnosis) were categorized as non-persistent. We assessed ET decision-making and used logistic regression to identify factors associated with non-initiation/non-persistence and to evaluate the association between non-persistence and recurrence. Results: By 18 months, 9% had not initiated ET. Black women had higher odds and women with a college degree had lower odds of non-initiation. Among 607 women who initiated, 20% were non-persistent. Younger age, being married/partnered, and reporting more weight problems were associated with higher odds of non-persistence; receipt of chemotherapy and greater hot flash and vaginal symptom burden were associated with lower odds of non-persistence. Adjusting for age and clinical characteristics, non-persistence was associated with lower odds of recurrence. Women who initiated were more likely to report shared decision-making than non-initiators (57% vs. 38%, p = 0.049), while women who were non-persistent were less likely to indicate high confidence with the decision than women who were persistent (40% vs. 63%, p < 0.001). Conclusion: Interventions to improve ET decision-making may facilitate initiation and address barriers to adherence in young breast cancer survivors. Trial registration: www.clinicaltrials.gov, NCT01468246.