1000 – Factors associated with survival in bilateral breast cancer: a retrospective case series

Abstract

Introduction: Bilateral breast cancer (BBC) represents 2%–12% of breast cancer cases, and can be synchronous or metachronous, accounting for approximately 2.9–3.9% and 4.1–4.6% of all new cases, respectively. Factors associated with a
worse prognosis include mutations in the BRCA1 and BRCA2 genes, biomarker expression, and lymph node involvement.
Methodology: A retrospective case series study, including 17 patients treated at the Oncocenter Clinic between 2004
and 2026. Survival curves were estimated using the Kaplan-Meier method and compared using the Log-rank test, considering a significance level of 5% (p<0.05). Variables such as age, histological classification, recurrence, genetic predisposition, interval between diagnoses, and current clinical status were analyzed. This study is part of a project approved by
the UESPI Ethics Committee under CAAE 30154720.0.0000.5209.
Results: The mean age at the time of the first diagnosis was 53 years. The metachronous form accounted for 76% of cases,
showing a higher average survival (189 months) compared to the synchronous form (66 months, p=0.006). An association
was observed between the pathological staging of the initial tumor and survival (p=0.024), with a prevalence of stage IA
in cases of death. The other variables analyzed were not relevant to survival.
Conclusions: Survival in patients with bilateral breast cancer in this case series was high and metachronous, with earlystage tumors demonstrating higher survival rates.
Ethics: Research Ethics Committee Approval (CAAE 30154720.0.0000.5209).