Abstract 4631: Pre-diagnosis comorbidity class, health-related quality of life, and treatment selection among older women with breast cancer
Authors: Lee Eunkyung , Zhu Jianbin , Hines Robert , Nam Eunji , Odahowski Cassie 
Published: September 2020

Abstract
Purpose of the study: The NCCN guidelines state that adjuvant radiotherapy (RT) can be omitted in older women with estrogen receptor (ER)-positive, node-negative early-stage (i.e., Tis and T1) breast cancer (ESBC). However, there is no specific algorithm to select a subgroup of women who can safely forgo RT. Older women commonly present with multiple comorbid conditions with different levels of functional limitations and health-related quality of life (HRQOL), which challenge the RT-decision process. This study aimed to understand pre-diagnosis comorbidity burdens in this patient group and to examine its relationship with HRQOL and treatment selection in a retrospective cohort study design.
Methods: From the SEER-MHOS database, we included 985 older women who were diagnosed at age ≥ 70 years, with ER-positive, node-negative ESBC between 1998 and 2013. SEER provides primary treatments (surgery and radiation), and MHOS provides self-reported comorbidity, functionality, and HRQOL. We used latent class analysis (LCA) to identify clinically distinct comorbidity burden classes. The associations between the comorbidity burdens with HRQOL and treatment selection (lumpectomy only, lumpectomy + RT, mastectomy, mastectomy + RT) were examined using generalized linear models.
Results: A mean age at diagnosis was 77 years, 81 % of patients were whites, and 43 % were married. A majority had stage I disease (80 %) with 20 % stage 0. About one fourth (26 %) had ≤ 1 comorbid condition, whereas 28 % had ≥ 4 comorbidities. LCA identified four distinct comorbidity burden classes; healthy (n=577, 58 %), low comorbidity with limited functionality (n=64, 7 %), moderate comorbidity with symptoms (n=247, n=25 %), and high comorbidity with highly limited functionality and symptoms (n=97, 10 %). Classes were distinguished by the presence or absence of comorbid conditions and functional limitations as well as symptoms. Comorbidity burdens were independently associated with HRQOL mental component summary (MCS-12) score (p &lt; .0001) and physical component summary (PCS-12) score (p &lt; .0001) but not with treatment selection (p = 0.096). In stage 0, age (p=0.025) and education level (p=0.024) were the independent predictors of treatment selection while age (p&lt;.0001), education level (p=0.0013), income (p=0.044), and obesity (p=0.026) determined the treatment selection in stage I.
Conclusions: Older women with ESBC can be described by four distinct comorbidity burdens that are independent predictors of HRQOL. However, it seems that the comorbidity burdens were not considered in the treatment selection process. Future studies need to address treatment outcomes (such as changes in HRQOL and survival) by comorbidity burdens to better guide treatment decisions.
Citation Format: Eunkyung Lee, Jianbin Zhu, Robert Hines, Eunji Nam, Cassie Odahowski. Pre-diagnosis comorbidity class, health-related quality of life, and treatment selection among older women with breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4631.