Assessment of endocrine therapy adherence in a nurse-led cancer survivorship clinic: Results from the Linking You to Support and Advice (LYSA) trial.

1627 Background: The care of those living with and beyond a cancer diagnosis requires dedicated cancer survivorship services to ensure optimal symptom control and quality of life. Supporting adherence to adjuvant endocrine therapy is also an essential component of care. We examined endocrine therapy adherence rates, and factors associated with non-adherence, in patients with early-stage breast cancer enrolling in a survivorship trial (LYSA). Methods: Women with early-stage hormone positive breast (n=168) cancers within 12 months of completing primary therapy, were enrolled in a randomized control trial with parallel arms (PMID 36357934). Experimental arm had access to nurse-led symptom management, dietetic consultation, and undertook bimonthly electronic patient reported outcome (ePRO). Active comparator group had access to conventional care and ePRO was completed at beginning and end of study. Endocrine therapy adherence was reported as the ability to take medication as prescribed over prior 4 weeks (Michigan Oncology Quality Consortium Adherence Tool), with response quantified as Excellent (adherence close to 100%), Very Good (80%), Good (60%), Fair (40%) and Poor (20%). Adherence Objective (Secondary) was adherence rate at 12 months after study entry in both arms, and factors associated with non-adherence. Results: A total of 148/168 women with breast cancer who completed the LYSA study reported adjuvant endocrine therapy use (74 experimental arm, 74 active comparator) during study conduct. Therapies included aromatase inhibitors (53%), tamoxifen (39%) and ovarian suppression combinations (8%). At study entry ≥ 80% adherence was reported in 74% of overall cohort (75% experimental, 72% comparator, p=0.7), with 1.6% reporting not taking any medication. By end of study (12 months), ≥ 80% adherence was reported in 74% overall (77% experimental, 71% comparator, p=0.4), while non-adherence rates were 2.9%. Among the pre-specified reasons for non-adherence at study end, “simply missing it” ranked highest (10%), and 5% “experienced side effects”. Post-menopausal patients were more likely than pre-menopausal to report excellent (versus sub-excellent) adherence at study end (OR 4.60, 95%CI 1.45 – 16.13, p = 0.012, adjusted for arm, age, and ECOG). Additional exploration of reasons for non-adherence will be presented. Conclusions: Adjuvant endocrine therapy adherence rates in both arms at 12 months after study entry collected via ePRO were good (≥ 90% reporting excellent or very good adherence). Additional factors potentially associated with non-adherence are being analyzed including self-care agency, symptom burden and quality of life. Clinical trial information: NCT05035173 .