1. In a prospective cohort study of over 3000 patients with breast cancer, more than 50% of patients discontinued their adjuvant hormone therapy by 5 years.
2. Risk factors for discontinuation of adjuvant hormone therapy in patients with breast cancer include family history of ovarian cancer, extremes in age, higher comorbidities, and use of co-current analgesics, antidepressants, sedatives, and GI medications.
Evidence Rating Level: 2 (Good)
Study Rundown: Adjuvant hormone therapy, such as aromatase inhibitors or tamoxifen, has been shown previously to significantly reduce the risk of recurrence and cancer-specific mortality in breast cancer patients. However, given the high frequency of treatment-related adverse events, previous studies have reported high rates of premature discontinuation of hormone therapy. However, there has been a limited number of studies that identify characteristics that increases risk of treatment discontinuation in this patient population. The purpose of this study was to identify predictors for discontinuation of adjuvant hormonal therapy among breast cancer patients. The authors prospectively followed over 3000 patients with breast cancer using national breast cancer and prescription drug registries in Sweden. After a follow-up period of 5 years, the authors found that over 50% of patients had premature discontinuation of hormone therapy. Risk factors associated with premature discontinuation included family history of ovarian cancer, age of diagnosis, high comorbidity scores, and use of co-current analgesia, antidepressants, sedatives, and gastrointestinal medications. The results of this study identifies key risk factors for discontinuation and support the development of targeted interventions to prevent future adjuvant hormone therapy discontinuation. However, the study is limited in the study design, as the use of registry data does not guarantee that the patient consumes the prescribed medication. Furthermore, use of symptom-relieving drugs may reflect other comorbid conditions unrelated to adjuvant treatment, which may cofound the results of this study.
In-Depth [prospective cohort]: This study included 3395 women diagnosed with breast cancer, treated in Sweden with adjuvant hormone therapy with tamoxifen or aromatase inhibitors between 2005 and 2008. Data was collected from the Stockholm-Gotland Breast Cancer Register and the Swedish Prescribed Drug Register. The primary outcome was discontinuation of adjuvant hormone therapy. Patients were monitored starting from their first prescription for hormone therapy until treatment discontinuation, death, recurrence, metastasis, endometrial cancer, venous thromboembolism and end of study period or completion of 5-year treatment. The authors collected information on baseline use of symptom-relieving drugs and hormone therapy, demographics, and comorbidities. At the conclusion of the study, baseline predictors for discontinuation included use of analgesics (HR: 1.33; 95% CI: 1.16-1.52), hypnotics/sedatives (HR: 1.24; 95% CI: 1.07-1.43) and gastrointestinal drugs (HR: 1.25; 95% CI: 1.08-1.43), as well as self-reported use of hormone replacement therapy (HR: 1.78; 95% CI: 1.14-2.76) during the first year of treatment. Other predictors included age <40 years (HR: 1.39; 95% CI: 1.08-1.78) or >65 years (HR: 1.15; 95% CI: 1.03-1.28) at diagnosis, higher Charlson comorbidity index (HR: 1.35; 95% CI: 1.03-1.76), and family history of ovarian cancer (HR: 1.55; 95% CI: 1.19-2.02).
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