Self-Reported Compliance With Adjuvant Endocrine Therapy in Young Women With Hormone Receptor-Positive Early Breast Cancer: A Real-World Study from a Tertiary Cancer Center in India.

BACKGROUND: Compliance with adjuvant endocrine therapy (ET) is crucial in hormone receptor-positive (HR+) early breast cancer (EBC), yet data from low- and middle-income countries (LMICs) remain scarce. This study evaluates compliance rates, identifies barriers to adherence, and assesses the impact on event-free survival (EFS). PATIENTS AND METHODS: This retrospective cohort study included 704 women aged 18 to 40 years with HR+ EBC treated at Tata Memorial Hospital, India, between 2015 and 2017. Compliance was assessed using a structured patient-reported questionnaire and was primarily defined as intake of ≥80% of prescribed ET therapy doses. Patients who completed at least 6 months of therapy were included in the primary compliance analysis. Factors associated with noncompliance were evaluated, and survival outcomes were compared between compliant and noncompliant groups. RESULTS: Among 653 evaluable patients, 436 (66.7%) were compliant with ET, and 217 (33.3%) were noncompliant. The most common justifiable barrier to noncompliance was treatment-related adverse effects (67.7%). Nonjustifiable barriers included economic barriers (53.9%), perception-related barriers (49.1%), and behavioral barriers (44.7%). Behavioral and economic barriers remained independently associated with noncompliance on multivariable analysis. At a median follow-up of 72.8 months (interquartile range 70.2-75.5), median EFS was not reached in the compliant group and was 86.9 months (95% confidence intervals [CI]: 64.5-NR) in the noncompliant group (P = .004). The estimated 5-year EFS was significantly higher among compliant patients compared with noncompliant patients [64.3% (95% CI: 59.6%-69.5%) vs. 53.4% (95% CI: 46.7%-60.9%)]. On Cox regression analysis, noncompliance was independently associated with inferior EFS (hazard ratios 1.44, 95% CI 1.12-1.86; P = .005). CONCLUSION: Noncompliance with ET is a clinically significant predictor of inferior outcomes in young women with HR+ EBC. Treatment-related toxicities were the most frequently reported barrier, while behavioral and economic barriers emerged as the principal independent predictors of noncompliance. Structured survivorship-focused interventions, including patient education, toxicity management, psychosocial support, and adherence monitoring strategies, are essential to improve long-term compliance and survival outcomes.