OBJECTIVES: Adjuvant endocrine therapy (AET) is the standard therapy for hormone receptor-positive (HR+) early breast cancer (EBC). It shows diverse treatment patterns in older women due to various factors. Given the complexity of AET use patterns, data visualization would be helpful in illustrating these patterns effectively. Our study aims to visualize the treatment patterns of AET within this population.

METHODS: This retrospective cohort study used the 2006-2019 Surveillance, Epidemiology, and End Results Program (SEER)-Medicare database and included women aged ≥66 with HR+ EBC who initiated AET - including anastrozole, exemestane, letrozole, and tamoxifen - between 2011 and 2014. The index date was the first date of AET use. Patients were categorized by age (66-79, ≥80), cancer stage at the first diagnosis (localized/regional), HER2 status (+/-), and the year of AET initiation. Treatment switch patterns were analyzed within these subgroups. Chi-square tests were used to assess differences in the number of AET switches and the initiation of AET for each subgroup. Sankey diagrams and sunburst plots were used to visualize distinctions in AET use patterns.

RESULTS: A total of 21,784 patients were included in our analysis. The sunburst plot showed that the 66-79 year old group had a higher frequency of drug switches compared to the ≥80 years age group. Patients with localized stage and HER2-were less likely to switch and more frequently began with tamoxifen as their initial AET, compared to those with regional stage and HER2+respectively. The Sankey diagram showed that a larger proportion of the 66-79 years age group initiated treatment with anastrozole, while tamoxifen usage was more prevalent in the ≥80 years age group.

CONCLUSIONS: In our study, data visualization methods were employed to simplify and clarify complex treatment patterns. We effectively showcased diverse AET drug usage trends and switching patterns, revealing differences by age, cancer stage, HER2 status, and index year.