Adherence and Compliance with Endocrine Treatment After Primary Breast Cancer Treatment: A Cross-Sectional Qualitative Study

Introduction Breast cancer is the most common cancer in women, with 80% being oestrogen receptor positive, requiring endocrine treatment to reduce recurrence. Treatment compliance is vital; however, 10-50% of patients take an incorrect dosage or discontinue therapy. This has shown a 20% mortality increase. Additionally, endocrine therapy has been said to negatively impact patient’s bone health. This study’s aim is to explore patient’s beliefs about endocrine treatment, how perception of medication risk and benefit affects adherence; as well as investigate the treatments effect on bone health. Methods: 100 patients diagnosed with oestrogen receptor positive breast cancer in 2020 were sent the Beliefs about Medicine Questionnaire-Adjuvant Endocrine Therapy (BMQ-AET). A further 101 semi-structured telephone interviews were conducted. Initial and recent DEXA scans were compared to assess bone density changes. Results The response rate for the questionnaire was 55%(N=55). 49 patients returned the postal paper survey, and 6 patients responded via QR code. 101 patients participated in semi-structured telephone interviews. 13 patients were non-adherent (8.3%). Non-adherent patients showed decreased BMQ-AET Necessity scores and higher scores for BMQ-AET Concerns subscales. Joint pain and poor quality of life were the most common reason for non-adherence, 58%(N=97), which confirmed the need for more help managing side effects. BMQ-AET NECESSITY SCORE N MEAN P-VALUE NON-ADHERENT 13 17.54 < 0.001 ADHERENT 143 10.86 BMQ-AET CONCERNS SCORE N MEAN P-VALUE NON-ADHERENT 13 13 0.002 ADHERENT 143 16.54 Of participants suitable for DEXA comparison, the majority (54.2%) showed an increase in bone density. Conclusion This study demonstrated good compliance to endocrine treatment. Non-adherent patients showed significantly low BMQ-AET necessity and high BMQ-AET concerns subscale scores. This highlights that patient’s non-adherent to AET have a lowered perception of necessity and greater concern regarding the medication, confirming a further need to address patient’s beliefs about endocrine treatment. DEXA comparison showed increased BMD, which challenges the previously held beliefs.