Long-Term Endocrine Therapy Adherence Following Stress Management for Breast Cancer

Molly Elise Ream

Despite life-saving potential, approximately half of women with hormone-receptor positive, early-stage breast cancer fail to complete the recommended 10-year course of Adjuvant Endocrine Therapy (AET). Prior research has elucidated several psychosocial barriers to AET adherence, including depression, anxiety, and poor social support; however, the value of controlling psychosocial distress to improve AET adherence has not yet been established. Of note, psychosocial distress is a primary target of Cognitive-Behavioral Stress Management (CBSM), a group-based intervention for women with newly diagnosed breast cancer. Ten-week CBSM has resulted in increased psychological adaptation to breast cancer. Further, CBSM was associated with less depressive symptoms and improved quality of life in breast cancer survivors at 11-year median follow-up. Given the evidence for the relationship between depression and psychological distress with AET adherence, it is plausible that women in CBSM had improved AET adherence compared to those receiving the control condition. Therefore, the present study examined whether stress management interventions based upon CBSM impacted AET medication adherence behaviors in the long-term.<o:p></o:p> The current study completed 7-year post-baseline follow-up of a cohort of women with newly diagnosed, early-stage breast cancer who received either a 5-week cognitive-behavioral therapy (CBT) intervention (n=55), a 5-week relaxation training (RT) intervention (n=70) (both based on the original CBSM protocol), or a 5-week group-based health education (HE) control (n=58). Women completed a psychosocial battery at T1 (prior to randomization), T2 (after group intervention/2-months post-baseline), T3 (6 months post-baseline), T4 (12 months post-baseline), and T5 (7-years post baseline). Adherence and persistence were measured by self-report using the Endocrine Therapy Medication Usage Questionnaire (ETMUQ), which was created by the research team, and was given at T5 long-term follow-up only. Potential mediators of adherence effects were measured at all 5 timepoints. These included depressive and anxious affect (Affect Balance Scale- depression and anxiety subscales), emotional well-being (Functional Assessment of Cancer Therapy-Breast Emotional Well-Being subscale), cancer-specific distress (Impact of Events Scale- Intrusion scale), social disruption (Sickness Impact Profile- Social Interaction scale), and stress management skills and confidence (Measure of Current Status- Relaxation and Coping Confidence subscales).<o:p></o:p>For intervention effects on persistence, we examined time to self-reported discontinuation by plotting an Unadjusted Kaplan-Meier Curve, and conducted log rank tests to determine group differences. Intervention effects on AET inconsistency were tested using structural equation modeling (SEM), in which the ETMUQ factors that were determined to be reliable and valid via Confirmatory Factor Analysis (CFA) were regressed on the intervention group controlling for covariates. To analyze potential psychosocial mediators of adherence effects, the change in each psychosocial construct over 5 timepoints was tested with Latent Growth Modeling (LGM). A basic change model of the repeated measures variables was constructed to explain the means and covariances of these variables, and a vector of treatment group was then added to the model to determine whether intervention predicted change. Finally, to test for mediation, the LGM was added separately to each factor of the ETMUQ, such that the slope of the variable predicted the adherence factor, and dummy vector of group predicted both the slope of the variable and the factor of the ETMUQ.<o:p></o:p>Of the women prescribed AET who completed long-term follow-up (n=59), less than half (n=28, 47.5%) reported still taking their medication and more than half (n=30; 50.8%) reported having at least some specific problems with adherence while taking the medication. Endorsed reasons for nonadherence were predominately related to routine interruptions and side effects.  Intervention condition did not predict persistence (i.e., time to discontinuation) to AET. However, there was an effect of intervention group on long-term adherence as measured by the ETMUQ, such that women receiving RT had significantly better adherence than those receiving CBT on the factor measuring Forgetfulness/Inconsistency, and marginally better adherence on the factor measuring Intentional Nonadherence. Women in the RT condition also demonstrated greater rate of change in the Measurement of Current Status-Relaxation subscale (MOCS-Relax) over the first year of treatment than did those in the CBT condition; however, there were no significant mediation effects of CBT versus RT on either factor of adherence through the slope of the MOCS-Relax.<o:p></o:p>The present study adds to the literature by demonstrating that relaxation training may have some impact on AET self-reported adherence in the long-term above and beyond any effect of CBT. Although the mechanism by which RT may improve adherence was not uncovered in the present analysis, future research should investigate whether relaxation training improves a patients’ self-efficacy to cope with the somatic symptoms related to AET adherence, or whether it may improve patients’ attention and awareness leading to less forgetfulness. In addition, future trials should investigate the ability of a psychosocial intervention that incorporates relaxation training with specific adherence counseling to improve long-term AET adherence and persistence. Overall, these findings illustrate the potential value of psychosocial interventions given shortly after diagnosis to improve AET adherence in the long-term.<o:p></o:p>

Long-Term Endocrine Therapy Adherence Following Stress Management for Breast Cancer

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