Supporting endocrine therapy adherence in US breast cancer survivors: pilot trial of a novel positive affect approach (‘THRIVE’)

Introduction Four of five breast cancer survivors will be prescribed adjuvant endocrine therapy (AET), an oral anticancer medication that dramatically reduces cancer recurrence but is often poorly adhered to. Reviews show small to null effects for existing AET adherence interventions, limited innovation in intervention approaches and a dearth of studies that target depression or low positive affect—key modifiable risk factors for poor adherence. Research design and methods Adapting behavioural innovations to the context of medication adherence, we developed and piloted THRIVE , a novel online positive affect intervention approach aimed at increasing AET adherence by reducing depression and increasing positive affect towards AET and broadly. Online THRIVE sessions were evaluated among breast cancer survivors prescribed AET (n=39) to assess: (1) acceptability and feasibility of this wholly novel approach; (2) patient-reported AET adherence, depression and affective outcomes; and (3) qualitative patient feedback, formally coded, to inform refinements. Results From preintervention to postintervention, participants reported significant increases in positive affect, positive associations with AET and reported AET adherence, as well as significant decreases in negative affect, anxiety and depression, ps<0.01, ds=0.28-0.77. The screened eligible-to-enrolled rate was 95.12%, and 100% of participants completed both THRIVE sessions and outcome surveys. Mean acceptability and feasibility ratings exceeded goals. Qualitative coding led to future recommendations, including the need to integrate help for managing AET side effects. Conclusion This study supports the promise of a novel positive affect intervention approach to supporting AET adherence among breast cancer survivors, particularly if combined with side effect support. Trial registration number NCT06388304 .