Comorbidity cluster trajectories across the care continuum in older women with breast cancer initiating adjuvant endocrine therapy.

INTRODUCTION

With the growing population of older breast cancer survivors, understanding how chronic comorbidities evolve across treatment and toward the end-of-life (EOL) is increasingly important. We aimed to characterize temporal and EOL patterns of comorbidity clusters before and after adjuvant endocrine therapy (AET) among women aged 66-79 years and ≥ 80 years with breast cancer.

MATERIALS AND

METHODS

We used the 2016-2019 SEER-Medicare data to identify women aged ≥66 years who initiated AET in 2017. Eligible patients had hormone receptor-positive, stage I-III breast cancer diagnosed within one year prior to AET initiation (index date). Comorbidities were defined using Clinical Classifications Software Refined (CCSR) codes. To identify comorbidity patterns, we applied agglomerative hierarchical clustering using Jaccard's dissimilarity index and Ward's minimum variance method to the top 50 CCSR categories across four periods: pre-index, post-year 1, post-year 2, and EOL.

RESULTS

We identified 11,551 women, of whom 11,050 were alive at the end of follow-up and 501 died during follow-up. Among the patients who were alive, more than 50% had ≥2 chronic conditions across the observation windows. Cardiovascular diseases and their associated risk factors showed the largest increase over time. The most consistent and prevalent cluster across post-year 1, post-year 2, and EOL was "cardiovascular and pulmonary diseases," including hypertension, coronary atherosclerosis, with additional respiratory and kidney-related conditions emerging near EOL.

DISCUSSION: Comorbidity clustering was common and persisted across observation windows, with cardiovascular and related conditions prominent and expanding near EOL. These patterns highlight the need for integrated cardio-oncology and geriatric co-management to address the complex care needs of older women receiving AET.