Original StudyEndocrine Therapy for Breast Cancer: Assessing an Array of Women's Treatment Experiences and Perceptions, Their Perceived Self-Efficacy and Nonadherence
Introduction
Prolonged adjuvant treatment with endocrine therapy markedly reduces the likelihood of breast cancer recurrence. Five years of tamoxifen, for example, reduces the risk of recurrence by 41%.1 However, the regimen duration and the various side effects combined with the prophylactic, and hence delayed, efficacy are likely to decrease adherence. Indeed, despite the efficacy of endocrine therapy, nonadherence and premature discontinuation by up to 30% of women have been reported.2, 3, 4, 5
To understand nonadherence to endocrine therapy, previous research has focused mainly on women's beliefs of the necessity or benefit of medicines.2, 5 Fink et al2 found that women with neutral or negative beliefs of the value of tamoxifen were more likely to discontinue tamoxifen. Grunfeld et al5 found that nonadherent women were more likely to report a belief that there was nothing to be gained from taking tamoxifen. However, other perceptions with regard to the efficacy such as knowledge perceptions have received much less attention.
Although side effects of endocrine therapy have received attention from various researchers as well,5, 6, 7, 8, 9 these were predominantly side effects considered important by or known to clinicians such as hot flushes, joint pain or stiffness, decreased libido, and gynecologic complaints. However, experience of unexpected side effects or side effects that are annoying to patients tend to receive less attention from clinicians and researchers.10 Similarly, practical problems such as problems with regard to taking tablets and packaging also have been understudied.5, 11 Furthermore, although previous studies examined the occurrence of side effects and general concerns and perceived harm about endocrine therapy, neither the level of worry evoked nor the level of bother imposed by specific side effects and practical problems have been studied.
Thus, in addition to previous findings, a comprehensive assessment of a wide array of women's specific experiences and perceptions with regard to the efficacy, the side effects, and the practical problems of endocrine therapy would be desired. Such a comprehensive assessment would be all the more important because a unifying causal model to explain nonadherence is lacking.2, 12 It is more likely that for different women, different experiences and perceptions explain nonadherence. Furthermore, it is likely that different experiences and perceptions will explain nonadherence of an unintentional nature caused by forgetting and nonadherence of an intentional more conscious nature.
The objective of this study was to examine women's specific experiences and perceptions with regard to endocrine therapy in a comprehensive manner. To prevent questionnaire burden, we developed the Tailored Medicine Inventory (TMI). The TMI assesses a wide array of experiences and perceptions in a feasible manner (see Patients and Methods).
Beyond women's endocrine therapy-associated experiences and perceptions, we examined whether women's perceived self-efficacy with regard to endocrine therapy use moderated associations of endocrine therapy experiences and perceptions with nonadherence. Perceived self-efficacy refers to one's perceived ability to execute a particular behavior.13 Previously, better adherence was found among patients who had a higher perceived self-efficacy with regard to medicine use and their ability to discuss treatment options.6, 14 Specifically, we examined whether higher perceived self-efficacy levels weakened positive associations between unfavorable experiences and perceptions and nonadherence.
Accordingly, we examined a wide array of experiences and perceptions with regard to endocrine therapy use, the extent to which these and perceived self-efficacy were associated with nonadherence and whether perceived self-efficacy moderated associations between women's experiences and perceptions and nonadherence.
Section snippets
Participants
Participants were women who were being treated with endocrine therapy to prevent recurrence of breast cancer or to slow its progression in the year before recruitment. Women were recruited through 2 hospitals and community pharmacies and 2 patient organizations. They were informed about the study via a personalized letter and a research leaflet. For ethical reasons, we excluded women with severe or terminal illness, psychiatric disorders (as inferred from their prescriptions), or for reasons at
Results
Of the 437 women who were invited through the pharmacies, 117 participated (response rate 27%), of the 161 women invited through the hospitals, 55 participated (34%), and of the 74 women invited through the patient organizations, 69 participated (response rate 93%). Thus, overall a total of 672 women were invited of whom an overall number of 241 women participated (response rate 36%). In Table 1, the demographic and clinical characteristics of the participants are presented. Women approached
Discussion
Treatment with endocrine therapy for the prevention of breast cancer recurrence is burdensome for many women. Doubts about the efficacy of endocrine therapy were frequently expressed. Meanwhile, side effects were frequently experienced or evoked worry, particularly hot flushes, libido decrease, joint ache and stiffness, and muscle cramps. The kinds of side effects and their frequencies were consistent with other findings.5, 6, 7, 8 Yet, side effects other than those that are often described in
Conclusion
Endocrine therapy is challenging for many women. Supporting women in coping with familiar and unfamiliar side effects is likely to decrease intentional nonadherence, and removing practical barriers is likely to decrease unintentional nonadherence, whereas improving perceived self-efficacy is likely to decrease both types of nonadherence.
Disclosure
Liset van Dijk received 2 unrestricted grants from BMS and Astra-Zeneca. Erica C.G. van Geffen is now employed at the Dutch Kidney Foundation (Nierstichting). All other authors have stated that they have no conflicts of interest.
Acknowledgments
Funding provided by the Netherlands Organization for Health Research and Development (ZonMw) (grant no. 152002028).
All women, the Diaconessenhuis Hospital, the Leiden University Medical Center, the pharmacists and pharmacy interns of participating community pharmacies are kindly thanked for their support. In addition, we thank the Dutch Breast Cancer Patients Society and the Amazones (organization for young women with breast cancer) for posting our call on their Web sites.
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