Distinct Patterns and Earlier Onset of Adverse Events in Young vs. Non-Young Breast Cancer Patients: A Real-World Analysis
Yongxin Li, Zijun Zhu, Jiatong Lu, Yan Li, Guoshuang Shen, Jiuda ZhaoIntroduction:
Age-related differences in Adverse Event (AE) reporting and reported Time to Onset (TTO) during systemic breast cancer treatment remain poorly characterized.
Methods:
We analyzed deduplicated reports from the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) from January 2004 through December 2024. Reports involving systemic antineoplastic therapy were classified as Young Breast Cancer (YBC; <40 years) or Non-Young Breast Cancer (NYBC; ≥40 years). Analyses included covariate-adjusted logistic regression, 1:1 propensity-score matching, alternative age cutoffs, treatment-context sensitivity analyses, and adjusted bootstrap median regression. Multiplicity was controlled using Bonferroni correction.
Results:
Among 71,426 reports (YBC, 4,292; NYBC, 67,134), adjusted reporting odds differed for 10 System Organ Classes (SOCs) and 6 Preferred Terms (PTs); four SOC and four PT associations remained after matching. Unadjusted reported TTO was shorter for 5 SOCs and 8 PTs in YBC. After adjustment, only gastrointestinal disorders (-4.23 days; 95% CI, -7.11 to -1.34) and pyrexia (-5.22 days; 95% CI, -8.79 to -1.65) remained significant. Findings varied across age definitions and treatment contexts.
Discussion:
This is the first study to systematically characterize AE reporting patterns in YBC through an integrated pharmacovigilance framework. Using FAERS data, we compared YBC and NYBC in terms of reported AE timing and adjusted reporting odds across SOC and PT levels.
Conclusion:
Selected AE reporting patterns differed by age, whereas most reported-TTO differences attenuated after adjustment. These exploratory reporting associations do not establish incidence, comparative toxicity, biological onset, or causality and require confirmation in datasets with exposure denominators and detailed treatment information.