GAINESVILLE, FL – What is the likelihood of breast cancer recurrence in nonmetastatic survivors who are nonadherent to endocrine therapy, the mainstay treatment to reduce BC recurrence risk?
That was the question addressed in a new study led by the University of Florida College of Pharmacy and including participation from the 7North Florida/South Georgia Veterans Health System; Geriatric Research Education and Clinical Center, which also is in Gainesville, FL.
In an article in the British Journal of Cancer, the study team noted that, during the first year of endocrine therapy use, nearly 30% of BC survivors are nonadherent, which could increase BC recurrence risk. Their efforts were to examine the association between endocrine therapy adherence trajectories and BC recurrence risk in nonmetastatic BC survivors.
The retrospective cohort study included Medicare beneficiaries in the United States with incident nonmetastatic BC followed by endocrine therapy initiation in 2010-2019 U.S. Surveillance, Epidemiology, and End Results (SSER)- linked Medicare data.
The researchers calculated monthly fill-based proportion of days covered in the first year of endocrine therapy, and then applied group-based trajectory models to identify distinct endocrine therapy adherence patterns. After the end of the first-year endocrine therapy trajectory measurement period, the risk of time to first treated BC recurrence within 4 years was measured using Cox proportional hazards models.
Results identified five trajectories of adherence to endocrine therapy in BC Stages 0-I subgroup, which involved 28,042 patients, and in Stages II-III subgroup with 7,781 patients.
“A trajectory of discontinuation before 6 months accounted for 7.0% in Stages 0-I and 5.8% in Stages II-III subgroups, and this trajectory was associated with an increased treated BC recurrence risk compared to nearly perfect adherence (Stages 0-I: adjusted hazard [aHR] = 1.84, 95% CI = 1.46-2.33; Stages II-III: aHR = 1.38, 95% CI = 1.07-1.77),” the authors wrote.
They concluded that nearly 7% of BC survivors who discontinued before completing 6 months of treatment were associated with an increased treated BC recurrence risk compared to those with nearly perfect adherence among Medicare nonmetastatic BC survivors.
Guidelines from the American Society of Clinical Oncology recommended that women with node-positive breast cancer receive extended endocrine therapy, including an aromatase inhibitor (AI), for up to a total of 10 years of adjuvant treatment. In addition, ASCO advised that many women with node-negative breast cancer should consider extended therapy for up to a total of 10 years of adjuvant endocrine treatment based on considerations of recurrence risk using established prognostic factors.
- Chang CY, Jones BL, Hincapie-Castillo JM, Park H, Heldermon CD, Diaby V, Wilson DL, Lo-Ciganic WH. Association between trajectories of adherence to endocrine therapy and risk of treated breast cancer recurrence among US nonmetastatic breast cancer survivors. Br J Cancer. 2024 Apr 18. doi: 10.1038/s41416-024-02680-0. Epub ahead of print. PMID: 38637603.
