Predicting Adherence to Tamoxifen for Breast Cancer Adjuvant Therapy and Prevention

Abstract

Treatment with the selective estrogen receptor modulator (SERM) tamoxifen for 5 years has produced dramatic breast cancer-related benefits in (a) the adjuvant setting, with 30% to 50% reductions in recurrence, contralateral disease, and mortality and (b) the prevention setting of healthy high-risk women, where tamoxifen reduces the risk of invasive and noninvasive breast cancer by 50%. Despite these striking data, adherence to tamoxifen is low, and low adherence is associated with poor survival. Although toxicity is a major predictor of poor adherence after starting therapy, pretreatment (baseline) predictors of poor tamoxifen adherence have been minimally studied. The adherence-survival link underscores the critical need to identify early predictors of poor adherence, and recent work is beginning to address this need. A major baseline predictor of poor adherence to prevention is current smoking, which is interestingly absent from studies of adherence to adjuvant therapy. Other important prevention adherence factors include breast cancer risk, extremes of age, non-white ethnicity, low socioeconomic status, and alcohol use. The strongest adjuvant therapy predictors are age (especially very young), ethnicity, and socioeconomic status. Future studies involving prospective systematic evaluation of these and other potential predictors in endocrine chemoprevention (e.g., other SERMs and aromatase inhibitors) are critical, as is the development of effective/targeted interventions to improve adherence and thus treatment outcomes in at-risk women.

Adherence to Endocrine Therapy in Breast Cancer Adjuvant and Prevention Settings

“…As reviewed (59,75), only modest information about factors associated with continued hormone therapy use is known and, importantly, few of the factors identified are easily modifiable. In addition, current medical claims databases, commonly used in adherence analyses, contain limited information on healthcare practice patterns or patient characteristics needed to identify new potentially modifiable factors.…”

Clinical Profiles Predict Early Nonadherence to Adjuvant Endocrine Treatment in a Prospective Breast Cancer Cohort

“…Clinically accessible markers that individually or in combination reliably predict that nonadherence may allow for interventions that decrease nonadherence and improve survival in women treated with adjuvant endocrine breast cancer therapy (30). The aim of this study was to investigate whether constitutional factors such as body mass index (BMI) and waist-to-hip ratio (WHR), lifestyle factors such as smoking, alcohol intake, and natural remedy use, tumor characteristics, detection mode, and type of surgery predict nonadherence to adjuvant endocrine breast cancer therapy, alone or in combination.…”

The Impact of Socioeconomic Status on the Use of Adjuvant Radioactive Iodine for Papillary Thyroid Cancer

“…Patients in low-SES communities often have limited financial resources and lack of support, preventing them from completing their recommended treatment course or follow-up care (16). This was demonstrated recently in patients with breast cancer, where rates of adherence to adjuvant tamoxifen were found to be significantly lower in patients of low SES (22).…”