Oncological Safety of Residual Tumor Size-Tailored Breast-Conserving Surgery After Neoadjuvant Chemotherapy Response

Neoadjuvant chemotherapy (NACT) facilitates breast-conserving surgery (BCS) in patients with initially inoperable breast cancer by reducing tumor size. This study assesses the oncological safety and efficacy of BCS tailored to post-NACT residual tumor size in patients with favorable responses.

In a prospective cohort study conducted at Assiut University Hospitals, Egypt (October 2020-April 2024), 100 female breast cancer patients with partial or complete response to NACT underwent oncoplastic BCS. Outcomes included local recurrence-free survival (LRFS), disease-free survival (DFS), overall survival (OS), and complication rates, assessed over a mean follow-up of 38 months with statistical analysis using Kaplan-Meier survival estimates and univariate Cox regression.

Patients had a mean age of 44 years, with a median follow-up of 38 months. Pre-NACT, 92% had T2/T3 tumors downstaged to 74% clinical T0/T1 post-NACT. Intraoperative frozen section ensured a 0% positive margin rate and 0% re-excision rate, with all margins confirmed negative on final pathology. The LRFS rates were 96% and 89% at 36 months. The DFS rate was 82% at 36 months. Triple-negative tumors had a higher risk of local recurrence. HER2+ cases were responsible for all distant metastases, with one case in the brain occurring at 11 months. The OS rate was 97% at 36 months.

Resection margins adjusted to the post-NACT tumor bed offer acceptable safety when negative margins "no ink in the tumor" achieved. The adequacy of the margins, nodal status, and molecular subtype help determine the risk of recurrence, supporting tailored adjuvant strategies.