Reoperation Versus Dose-Escalated Radiotherapy for Ductal Carcinoma In Situ at the Surgical Margin After...

The aim of this study was to compare local recurrence (LR) rates in patients with ductal carcinoma in situ (DCIS) at the surgical margins after breast-conserving surgery (BCS).

This single-center, retrospective study included patients diagnosed with invasive ductal carcinoma (IDC) who underwent BCS at National Cancer Center between 2014 and 2020. Patients with DCIS at the surgical margin were eligible for inclusion. Those who did not undergo re-excision received whole-breast radiotherapy with an escalated tumor bed boost of 15 Gy in five fractions. The 5-year breast cancer recurrence rates were estimated using the Kaplan-Meier method, and prognostic factors were evaluated using univariate and multivariate Cox proportional hazards regression models.

Among the 235 eligible patients, 115 underwent re-excision (Re-excision + group), and 120 did not (Re-excision - group). With a median follow-up of 5.0 years (range, 3.1-6.6 years), the 5-year LR rate was 6.1% in the Re-excision + group and 5.8% in the Re-excision - group (log-rank p = 0.9). Re-excision was not significantly associated with differences in LR rates in multivariate analysis.

In cases where DCIS was present at the surgical margin after BCS, re-excision was not associated with a lower LR rate compared with dose-escalated radiotherapy. This study did not assess late radiation-related toxicities, such as breast fibrosis, which are important considerations for treatment decision-making. These findings should be interpreted with caution because of the retrospective design and limited event rate. Further prospective studies are warranted to determine optimal management strategies.