Restarting Adjuvant Endocrine Therapy for Breast Cancer

October 6, 2017

Restarting Adjuvant Endocrine Therapy for Breast Cancer

  1. William J. Gradishar, MD

Disease-free survival is significantly improved in patients who restart therapy versus those who do not restart after discontinuation.

  1. William J. Gradishar, MD

Although adjuvant endocrine therapy has clearly been shown to reduce the risk for recurrence of estrogen receptor–positive, early-stage breast cancer, the rate of treatment noncompliance or nonadherence among patients is estimated to be greater than 50%. To determine the impact of discontinuing and then restarting endocrine therapy, investigators conducted a population-based cohort study by linking data from Swedish breast cancer and prescribed drug registers and patient-reported questionnaires.

Women who received a diagnosis of breast cancer between 2005 and 2008 and had received a prescription for adjuvant tamoxifen or an aromatase inhibitor were followed until 2015. Restarting treatment was defined as filling at least two prescriptions after a discontinuation of at least 90 days. Of 1819 participants, 1607 were categorized as treatment continuers, 953 were treatment restarters, and 511 were treatment nonrestarters.

Disease-free survival was significantly improved in treatment restarters versus nonrestarters (adjusted hazard ratio, 0.61; P=0.006). Characteristics of patients unlikely to restart included age younger than 50 years, higher Charlson comorbidity score (≥2), smaller tumor size (<2 cm), lymph node–negative disease, HER2-negative disease, a negative family history, use of hormone replacement therapy, use of medications to reduce symptoms, and evidence of switching between tamoxifen and aromatase inhibitors.


These results demonstrate the benefits of restarting adjuvant endocrine therapy for breast cancer patients and provide clues about which patients tend not to restart. The importance of adjuvant endocrine therapy should be highlighted for breast cancer survivors who are scheduled for long durations of treatment.

Editor Disclosures at Time of Publication

  • Disclosures for William J. Gradishar, MD at time of publication Editorial boards Clinical Breast Cancer; Oncology Leadership positions in professional societies National Comprehensive Cancer Network (Chair, Breast Cancer Panel)


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