Recurrence Patterns and Long-Term Results After Curative Surgery for Patients With Breast Cancer

Background: The current study aimed to examine second breast cancer (SBC) risks associated with breast-conserving surgery (BCS) and unilateral mastectomy among breast cancer (BC) survivors.

Methods: The study enrolled patients with diagnoses of stages I to III BC who underwent surgery between 2000 and 2019. Fine-Gray competing risk regression models were used to estimate the cumulative incidence of SBC and to evaluate the associations between clinical factors and SBC development. Poisson regression analysis was performed to assess the risk for SBC after BCS compared with mastectomy by age and latency period. The Kaplan-Meier method was applied to examine survival between patients undergoing breast-conserving therapy (BCT) and those undergoing mastectomy for SBC.

Results: Among 740,349 patients, 467,480 underwent BCS, and 272,869 underwent mastectomy. The 10-year cumulative incidence of mastectomy was 3.77% for SBC and 2.11% for BCS. Compared with mastectomy, BCS was associated with a significantly higher risk of LR and a modestly elevated risk of contralateral breast cancer (CBC). The significant risk factors for SBC were age at initial BC diagnosis, race, marital status, year of diagnosis, tumor size, histology, molecular subtype, cancer stage, metropolitan status, type of surgery, and radiotherapy. Dynamic risk assessments showed that the relative risk of SBC after BCS versus mastectomy decreased with advancing age, but increased with longer follow-up periods.

Conclusions: This cohort study showed that BC survivors undergoing BCS have a higher risk of SBC than those undergoing mastectomy. With the ongoing evolution of surgical options, achieving optimal long-term outcomes necessitates a more comprehensive assessment that balances oncologic efficacy with patient-centered outcomes.