Treatment Side Effects & Nonadherence among Women Taking Adjuvant Endocrine Therapy for Breast Cancer: The Role of Psychological Factors

Abstract

Nonadherence to adjuvant endocrine therapy with either tamoxifen or aromatase inhibitors significantly increases the risk of breast cancer recurrence. Side effects are a key driver of nonadherence to these treatments. As part of this doctoral research, two studies were conducted to explore the possibility that psychological factors contribute to both the experience of side effects and treatment nonadherence among women taking adjuvant endocrine therapy. The first study explored factors associated with nonadherence to aromatase inhibitors. One hundred and fifty-three women diagnosed with early-stage breast cancer responded to the crosssectional survey. Results showed that women who reported less personal control over cancer recurrence, more severe consequences from the diagnosis, and lower beliefs in the necessity of taking medication were more likely to be nonadherent. The results also highlighted the significant proportion of women reporting symptoms from aromatase inhibitors. The second study examined predictors of symptom reports and nonadherence among women taking tamoxifen or aromatase inhibitors. One hundred and twenty women completed surveys prior to treatment and again three months later. Results showed that lower illness coherence beliefs and higher symptom severity were the strongest predictors of nonadherence measures. Symptoms were predicted by factors such as fear of recurrence and patient beliefs including low personal control over cancer recurrence, and high perceived sensitivity to the effects of medicines. Finally, results highlighted the dynamic nature of these associations over time. Taken together, the results of this research indicate that illness and medication beliefs contribute unique variance to symptom reports and nonadherence among women taking adjuvant endocrine therapy. These novel findings have potential clinical implications. First, screening for key patient beliefs prior to treatment may help to identify patients at risk of higher symptom reports and nonadherence. Second, there may be benefit to supplementing current pharmacological approaches to symptom management with psychological approaches. Finally, patient beliefs appear to be viable targets for interventions designed to improve treatment adherence. Future research is needed to explore the effects of interventions aimed at changing illness and medication beliefs, and to determine their optimal timing in order to improve clinically relevant outcomes among women taking adjuvant endocrine therapy.