Endocrine therapy for breast cancer: assessing an array of women's treatment experiences and perceptions, their perceived self-efficacy and nonadherence.

Background: Although adjuvant endocrine therapy effectively prevents breast cancer recurrence, nonadherence rates are substantial. We therefore examined associations of women's experiences and perceptions regarding the efficacy, side effects, and practical problems of endocrine therapy with nonadherence. Furthermore, we examined whether women's perceived self-efficacy moderated these associations.

Patients And Methods: Two hundred forty-one breast cancer patients participated. Using the electronic Tailored Medicine Inventory, which enables skipping of irrelevant items, experiences and perceptions were assessed in a comprehensive yet feasible manner. Adherence was assessed according to self-report and evaluated for agreement with adherence estimated from pharmacy refill data.

Results: A substantial number of women doubted the efficacy of endocrine therapy, were worried about and/or had experienced hot flushes, loss of libido, joint ache, and/or practical problems with regard to information, intake, and packaging. Experience of practical problems (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.0-5.8) and perceived self-efficacy with regard to medicine intake (OR, 0.5; 95% CI, 0.4-0.7) were associated with unintentional nonadherence. Number of side effects experienced (OR, 1.2; 95% CI, 1.05-1.4) and perceived self-efficacy with regard to learning about medication (OR, 0.6; 95% CI, 0.4-0.96) were associated with intentional nonadherence. Perceived self-efficacy did not moderate associations between women's treatment experiences and perceptions and nonadherence.

Conclusion: Endocrine therapy is challenging for many women. Targeting women's specific experiences and perceptions and improving their perceived self-efficacy is likely to decrease intentional and unintentional nonadherence.