10706 Background: Few studies that have investigated the long-term effect of MRT in DCIS, have demonstrated conflicting results. Mount Nittany Medical Center (MNMC) is located in an agricultural, ethnically-homogenous (Non-Hispanic White) county in PA. To the best of our knowledge, there have been no similar studies conducted on such populations. Our study has investigated the effect of MRT at SMR on overall survival (OS) and event-free survival (EFS) of patients with DCIS. Methods: All women diagnosed with DCIS from 04/1992 to 06/2005 at MNMC were deemed eligible. Log-rank statistics and Cox proportional hazard models (CPHM) were used for obtaining survival rates. Results: Of the 266 eligible women analysis were performed on 167 women (age range 33–89 years; median 56 years) with complete data on diagnosis, surgical margins and treatment modalities. With median follow-up time of 4.6 years (range 0.03–11.6years), 148 (88.6%) patients had no residual tumor at SMR. 78 (46.7%) patients received radiation therapy (RT) ± hormonal therapy (HT), 42 (25.2%) received HT ± RT. The CPHM demonstrated no statistical significance of MRT on OS (hazard ratio 2.9, p = 0.19), and EFS (hazard ratio = 1.9, p = 0.43) after adjusting for treatment and age. Univariate 5-year OS rate in patients with no MRT was 93.9% (95% confidence interval (CI) 87.6% to 97.1%), versus 89.2% (95% CI 63.1% to 97.2%) in patients with MRT (p-value = 0.38). Five-year EFS was observed to be 92.6% (95% CI 85.6% to 96.3%) in patients with no MRT, versus 89.2% (95% CI 63.1% to 97.2%) in patients with MRT (p-value = 0.49). Conclusions: In our study, patients with DCIS who have MRT at surgical margin of resection have a 2.9 times the risk of death and 1.9 times the risk of recurrence as compared to patients with no MRT. However, this difference is statistically not significant over time. No significant financial relationships to disclose.