Adjuvant chemotherapy and survival outcomes in older women with HR+/HER2- breast cancer: a propensity score-matched retrospective cohort study using the SEER database

Xindi Ma; Shang Wu; Xiangmei Zhang; Nannan Chen; Chenhui Yang; Chao Yang; Miao Cao; Kaiye Du; Yunjiang Liu

doi:10.1136/bmjopen-2023-078782

Adjuvant chemotherapy and survival outcomes in older women with HR+/HER2- breast cancer: a propensity score-matched retrospective cohort study using the SEER database

BMJ Open. 2024 Mar 15;14(3):e078782. doi: 10.1136/bmjopen-2023-078782.

Authors

Xindi Ma^#^{1

2}, Shang Wu^#^{1

2}, Xiangmei Zhang^{2

3}, Nannan Chen⁴, Chenhui Yang^{1

2}, Chao Yang^{1

2}, Miao Cao^{2

3}, Kaiye Du⁵, Yunjiang Liu^{6

2}

Affiliations

¹ Breast Center, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
² Hebei Provincial Key Laboratory of Tumor Microenvironment and Drug Resistance, Shijiazhuang, Hebei, China.
³ The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
⁴ Department of Pharmacology, Hebei Medical University, Shijiazhuang City, China.
⁵ Department of Radiotherapy, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
⁶ Breast Center, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China lyj818326@outlook.com.

^# Contributed equally.

Abstract

Objectives: This study aimed to investigate the impact of adjuvant chemotherapy (ACT) on survival outcomes in older women with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer (BC).

Design: A retrospective cohort study using data from the Surveillance, Epidemiology, and End Results database, which contains publicly available information from US cancer registries.

Setting and participants: The study included 45 762 older patients with BC aged over 65 years diagnosed between 2010 and 2015.

Methods: Patients were divided into two groups based on age: 65-79 years and ≥80 years. Propensity score matching (PSM) was employed to balance clinicopathological characteristics between patients who received ACT and those who did not. Data analysis used the χ² test and Kaplan-Meier method, with a subgroup analysis conducted to identify potential beneficiaries of ACT.

Outcome measures: Overall survival (OS) and cancer-specific survival (CSS).

Results: Due to clinicopathological characteristic imbalances between patients with BC aged 65-79 years and those aged ≥80 years, PSM was used to categorise the population into two groups for analysis: the 65-79 years age group (n=38 128) and the ≥80 years age group (n=7634). Among patients aged 65-79 years, Kaplan-Meier analysis post-PSM indicated that ACT was effective in improving OS (p<0.05, HR=0.80, 95% CI 0.73 to 0.88), particularly in those with advanced disease stages, but did not show a significant benefit in CSS (p=0.09, HR=1.13, 95% CI 0.98 to 1.31). Conversely, for patients aged ≥80 years, ACT did not demonstrate any improvement in OS (p=0.79, HR=1.04, 95% CI 0.79 to 1.36) or CSS (p=0.09, HR=1.46, 95% CI 0.69 to 2.26) after matching. Subgroup analysis also revealed no positive impact on OS and CSS.

Conclusions: Patients with HR+/HER2- BC ≥80 years of age may be considered exempt from ACT because no benefits were found in terms of OS and CSS.

Keywords: SEER; adjuvant chemotherapy; breast cancer; older women; propensity score-matched.

MeSH terms

Aged
Aged, 80 and over
Breast Neoplasms*
Chemotherapy, Adjuvant / methods
Female
Humans
Propensity Score
Retrospective Studies
SEER Program