Is radiotherapy necessary for intermediate risk ductal carcinoma in situ after breast conserving surgery?

Identifying ductal carcinoma in situ (DCIS) patients at highest risk for recurrence after breast conserving surgery (BCS) remains a clinical concern. Subjecting all such patients to radiotherapy may be unnecessary. The Van Nuys Prognostic Index (VNPI) is a simple scoring system for predicting the risk of local recurrence in patients with DCIS. We reviewed patients with DCIS applying the VNPI score system. A total of 184 DCIS patients who underwent surgery at our institution between January 2003 and December 2011 were identified. Patients were not treated according to VNPI guidelines; rather, radiation therapy was applied at each surgeon's discretion. All patients with hormonal receptor positive tumors were treated with hormonal therapy. Pathology reports were reviewed and VNPI scores of each DCIS calculated. Of the 184 patients, 52 (28.3%), 115 (62.5%) and 17 (9.2%) had low, intermediate and high VNPI scores, respectively. Six of the 184 patients (3.3%) developed ipsilateral local recurrence, five in the intermediate and one in the high VNPI score group. Of the five in the intermediate group, three (60%) were in patients with ER-negative tumors. VNPI score itself was not associated with recurrence (P = 0.145). Factors associated with recurrence included tumor size (hazard ratio [HR] 6.88), grade (HR 9.07) and hormone receptor status (HR 11.75). Radiotherapy did not significantly improve recurrence rates in patients with low and intermediate risk DCIS, especially in those with ER-positive tumors. Radiotherapy can be omitted in patients with ER-positive intermediate score DCIS and in patients with low score DCIS.