Identification of high- and low-risk groups for ipsilateral recurrence within 10 years after breast-conserving surgery for ductal carcinoma in situ and personalized treatment: a retrospective study.

Background: Breast-conserving surgery (BCS) is widely used for ductal carcinoma in situ (DCIS), but ipsilateral breast tumor recurrence (IBTR) remains a significant clinical challenge, highlighting the need for reliable predictive models to guide personalized treatment strategies. This study aims to fill the gap by developing a predictive model for IBTR in DCIS patients who have undergone BCS. Methods: A cohort of 40,770 DCIS patients who underwent BCS between 2000 and 2008 was identified from the Surveillance, Epidemiology, and End Results dataset. Chi-squared tests and logistic regression analyses were conducted to identify significant predictive factors for IBTR. These variables were incorporated into nomograms predicting the 5- and 10-year recurrence probabilities. The model was then used to categorize patients into risk groups. Results: The nomograms demonstrated good calibration and discriminative ability for predicting 5- and 10-year IBTR probabilities. Patients were stratified into extremely high- and low-risk groups. Among patients receiving adjuvant radiotherapy, those in the standard-risk group showed significantly lower recurrence rates compared to the extremely high-risk group (P<0.001). For the extremely low-risk group, no significant difference in recurrence risk was observed between patients who received adjuvant radiotherapy and those who did not (P=0.065). Conclusions: Patients with a recurrence rate above 10% were classified as extremely high-risk and may benefit from intensified treatment. Conversely, patients with a recurrence rate below 5% were considered extremely low-risk, suggesting that treatment could be safely de-escalated.