Outcomes of Second Breast-Conserving Surgery Without Reirradiation for Breast Tumor Recurrence.

[BACKGROUND] Breast-conserving therapy (BCT), combining breast-conserving surgery (BCS) and radiotherapy (RT), is a standard treatment for early stage breast cancer. Despite its effectiveness, patients remain at risk for ipsilateral breast tumor recurrence (IBTR). While mastectomy is traditionally recommended for IBTR, a second BCS with reirradiation (ReRT) has emerged as an alternative. However, there are limited data on outcomes for second BCS without ReRT in low-risk patients. This study aims to assess the outcomes of second BCS without ReRT in patients with low-risk IBTR.

[PATIENTS AND METHODS] This retrospective cohort study included patients with low-risk IBTR who underwent second BCS without ReRT at the Curie Institute between 2001 and 2023. Eligible patients had hormone receptor-positive, HER2-negative tumors with low histological grade and a size ≤ 2 cm without evidence of lymph node involvement. Data were collected on local recurrence-free survival (LRFS), metastatic recurrence-free survival (MFS), and overall survival (OS).

[RESULTS] Among 154 patients who underwent second BCS without ReRT, 119 had invasive carcinoma and 35 had ductal carcinoma in situ (DCIS). Over a median follow-up of 50 months, 11 patients (7.1%) experienced a second local recurrence, and 6 patients (3.8%) developed metastatic recurrence. Of these 6 metastatic cases, only 2 were associated with synchronous local recurrence. Importantly, no deaths were attributed to breast cancer in this cohort, highlighting the viability of this approach in low-risk patients. Overall survival at 36 months was 98% for invasive carcinoma and 100% for DCIS.

[CONCLUSIONS] Second BCS without ReRT offers favorable outcomes with low rates of recurrence and metastasis and no breast-cancer-specific mortality in selected low-risk IBTR patients, providing a viable alternative to mastectomy. Further studies with longer follow-up are necessary to confirm these findings and evaluate their applicability in higher-risk populations.