Abstract PO5-02-11: Is There A Survival Benefit With Adjuvant Chemotherapy Use In Elderly Breast Cancer Patients? A Retrospective Study Using The National Cancer Database
Authors: Kumar Prashanth Ashok , Sravanthi Metlapalli Venkata , Wang Dongliang , Huang Danning , Sivapiragasam Abirami 
Published: May 2024

Background

Geriatric patients (Age &gt;=65 years) with Breast Cancer (BC) face a unique challenge due to the relatively lower functional status, as well as co-existing comorbidities. Studies like the recently published meta-analysis by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) group provide irrefutable evidence for the recurrence free survival benefit of anthracycline and taxane based adjuvant chemotherapy (ACT) regimes in early-stage BC patients. However, the age range of the trials analyzed ranged between 46-55 years, with underrepresentation of the geriatric group. The question on whether ACT results in an overall survival (OS) benefit for the elderly remains at large, which we hope to answer through our study.

Methods

The 2019 National Cancer Database (NCDB) was used to extract patients aged &gt;= 65 years with breast cancer. We included stage 1-3 patients and stratified them into those who received ACT (ACT+) and those who did not (ACT-). Patients who received ACT were identified from the columns that specified the times of events from diagnosis or from the column for systemic therapy-surgery sequence. Patients should have had definitive surgery for their BC management to be included. Odds Ratio (OR) from logistic regression was used to analyze the utility of ACT based on various factors. Kaplan Meier (KM) survival curves and Hazard Ratio (HR) estimates from multivariate cox model was used to compare OS outcomes.

Results

Our cohort had 866,071 (ACT+: 642721, ACT-:223350) patients. The age distribution showed that ACT+ had 86.45% in the 65-80 years group and 13.55% in the &gt;80 years group. ACT- had 68.32% aged 65-80 and 31.68% &gt;80 years. The distribution of various demographic, pathologic and clinical factors by ACT use are shown in Table 1. Factors associated with ACT use based on OR estimates are shown in Table 2. ACT use is more likely in younger age group (65-80), lower comorbidity score, poorly differentiated and undifferentiated tumors, ER/PR negativity, T2 and lymph node positivity, those who underwent partial mastectomy and regional lymph node surgery, and HER2 positivity. Both 5-year (86.3 vs 74.2%) and 10-year (66 vs 50.8) OS were better with ACT+ (Table 2). The HR using propensity score (PS) weighted cox model revealed a higher hazard rate on omitting ACT [1.436, 95% Confidence Interval (CI) 1.417,1.456, p&lt; .0001] (Table 2). HR estimates between ACT- vs ACT+, stratified by subgroups [Age (65-80, &gt;80), T stage, grade (G), HER2] favored ACT use in all groups except G1 tumors (Table 3).

Discussion

Our study using a large national database, supports the use of ACT in the geriatric BC population by showing a clear OS advantage of 15.2% at 10 years. This benefit was observed even in BC patients aged more than 80 years with a HR of 1.683 when compared to ACT-, as represented in Table 3. While the existing literature provides robust evidence for ACT use in situations such as a high oncotype recurrence score, our study provides real-world evidence from a population-based dataset to supports its use in the elderly, including those above 80 years. The geriatric assessment recommended by the American Society of Clinical Oncology guideline for geriatric oncology should be followed in this setting. Utilization of geriatric assessment tools among oncologists has been poor with a survey revealing that 60% of providers did not utilize these tools in making treatment decisions. Limitations of our study include the potential for missing confounding factors and the retrospective nature of the study using a large database.

Table 1 Demographic, pathological, and clinical characteristics of the study population and their distribution based on ACT use.

Table 2 Odds Ratio for ACT use, KM survival curves and HR estimates of ACT use

Table 3 HR estimates of mortality for ACT- vs ACT+ stratified by various subgroups

Citation Format: Prashanth Ashok Kumar, Metlapalli Venkata Sravanthi, Dongliang Wang, Danning Huang, Abirami Sivapiragasam. Is There A Survival Benefit With Adjuvant Chemotherapy Use In Elderly Breast Cancer Patients? A Retrospective Study Using The National Cancer Database [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-02-11.