Treatment of ductal carcinoma in situ (DCIS) with lumpectomy and accelerated whole breast radiation therapy with concomitant boost (ARTB).

Abstract

93 Background: The efficacy of accelerated radiation therapy (RT) for treating early stage invasive breast cancer has been established (Whelan T et al: NEJM, February 2010). But the role of accelerated schedules in treating patients with DCIS still needs to be defined. We have previously described the feasibility and low toxicity when using ARTB after lumpectomy (Chadha M et al: Int J Radiat Oncol Biol Phys 2007; 69). The objective of this study is to evaluate early outcomes in patients with DCIS treated with lumpectomy and ARTB, and to compare local recurrence rates of ARTB and conventional fraction (fr) RT with sequential boost (CRT). Methods: This study includes patients diagnosed to have primary DCIS treated with lumpectomy and RT. Patients with DCIS who had history of contralateral synchronous or metachronous invasive cancer were excluded. We identified 215 patients from our breast cancer database as having met this selection criteria; 54 patients received ARTB on an IRB approved protocol, and 161 patients matched by prognostic factors constituted the comparative CRT group. ARTB delivered 40.5Gy in 15fr to the breast, and with concomitant boost 45Gy in15fr was delivered to the lumpectomy boost volume. CRT delivered 46.8Gy in 26fr with sequential boost of 14Gy in 7fr. The patients were well matched with no significant difference in the distribution of known prognostic factors including age, nuclear grade, margin status, receptor status, and Body Mass Index between the groups. Results: The overall median follow up was 3.5 years (0.5 years–11.4 years). Actuarial 5-year local relapse-free survival was 95%. The actuarial 3-year local relapse rate was 2% and 0% for CRT and ARTB groups, respectively (p = 0.22). Local recurrence was observed in 9 patients with a median time to failure of 4.3 years (0.5 years to 8.6 years); 4/9 had grade 3 DCIS; 1 patient with grade 3 had close final margin (<1 mm); 5/9 patients received hormone therapy. Conclusions: With the follow up to date, we observed excellent outcomes in patients with DCIS treated by lumpectomy and RT. These preliminary results suggest comparable local control between ARTB and CRT. Additional studies and longer follow-up are needed.