Adjuvant treatment in elderly breast cancer patients: the experience of an oncology center in São Paulo

Introduction: The estimated number of new breast cancer cases in Brazil for each year of the 2023 to 2025 triennium is 73,610. The aging global population has led to an increase in breast cancer cases among the elderly. However, this age group is less likely to receive standard oncological treatment with appropriate protocols, affecting survival rates.

Study End Points and Trial Design: This is a retrospective cohort study, designed from the records of 1,160 breast cancer patients aged 75 years or older undergoing treatment for early-stage breast cancer, treated between January 2018 and January 2021 at the Brazilian Institute of Cancer Control (IBCC). The aim of the study was to identify the frequency at which standard adjuvant chemotherapy was administered at this oncological reference center, assess the safety profile. Considering the variables: age at diagnosis, immunohistochemistry, histological grade, and clinical stage, the propensity score matching method made it possible to form pairs with similar characteristics between the chemotherapy (QT) and non-chemotherapy (non-QT) groups and determine the association with disease-free survival and overall survival.

Results: A total of 162 patients were eligible and divided into two groups: adjuvant chemotherapy (n = 47) and no adjuvant chemotherapy (n = 115). The frequency of adjuvant chemotherapy indication was 29%. The preferred regimen was Docetaxel and Cyclophosphamide (TC) in 36.2% of cases. The safety profile was acceptable, with grade 3 and 4 toxicity (Common Terminology Criteria for Adverse Events): hematological toxicity in 6.4%, peripheral neuropathy in 4.9%, no reports of anthracycline-related cardiotoxicity, hospitalization in 8.5%, and no deaths related to adjuvant therapy. After using propensity score matching, 29 balanced pairs were formed, and no association was found between the use of adjuvant chemotherapy and disease-free survival (HR 1; 95% CI 0.25-3.99; p = 0.97) or overall survival (HR 0.23; 95% CI 0.03-2.07; p = 0.19).

Conclusion: The study demonstrates the importance of understanding the profile of elderly breast cancer patients for accurate indication of adjuvant chemotherapy. Additionally, it confirmed with real-world data an acceptable safety profile for standard-of-care protocols. Studies with larger sample sizes and prospective designs may address this gap in the literature: the impact of adjuvant chemotherapy on survival in the elderly population.

Corresponding author: Andressa Liz Candido (e-mail: andressalizcandido@gmail.com).