Mastectomy Scar Boosts And Dose Escalation To The Chest Wall Are Not Needed To Achieve Excellent Local Control In Patients With Locally Advanced And Inflammatory Breast Cancer

Prior studies have suggested the need for increased radiation therapy (RT) doses to the chest wall and/or mastectomy scar boosts to obtain acceptable local control for patients with locally advanced (LABC) or inflammatory breast cancer (IBC). The purpose of this study was to analyze the local control rates and sites of failure for patients with LABC and IBC treated with multimodality therapy. From 1984 to 2003, 148 patients with non-metastatic LABC and IBC were treated with definitive trimodality therapy at Fox Chase Cancer Center. 47 patients had stage IIB disease, 31 patients had stage IIIA disease, 20 patients had IIIB disease and 50 patients had IBC. The median age was 52 years (range 29–89). A modified radical mastectomy was performed in all patients. 134 patients (90%) received chemotherapy ± Tamoxifen and 14 patients (10%) received Tamoxifen alone as systemic therapy. Post-mastectomy RT was delivered to the chest wall and regional lymph nodes in 142 patients (96%). RT was delivered to the breast and regional lymph nodes after chemotherapy but prior to mastectomy in 6 patients (4%). The median dose to the chest wall/intact breast was 50 Gy (range 34–50 Gy), with a daily fraction size of 2 Gy. Bolus was used in all patients and was placed on the chest wall/breast every other day. Eight patients received a mastectomy scar boost (median dose 10 Gy). The dose to the supraclavicular region was 46 Gy in all patients; 45 patients received a posterior axillary boost of 10 Gy. No patients had internal mammary nodal radiation. The median follow-up was 48 months. Outcome was evaluated for patterns of failure, cause-specific survival, overall survival and complication rates utilizing Kaplan-Meier methodology and comparisons were made using the log-rank test. Cox multivariate regression (MVA) was used to assess independent predictors of outcome. The overall 5-year actuarial rate of local control was 95%. There were only six local failures. Four of these local failures involved the chest wall away from the scar, and none had a scar boost. The other 2 local failures were located within the region of the mastectomy scar, and 1 of these 2 scar failures received a scar boost. The 5-year overall rates of local control, distant metastases, cause-specific survival and overall survival were 95%, 57%, 67% and 62%, respectively. The 5-year local control rates for patients with IBC, stage IIIA disease, stage IIIB disease and stage IIB disease were 92%, 96%, 95% and 95%, respectively. There were no radiation-related complications observed with these RT doses. On MVA, the use of a scar boost and dose to the chest wall had no statistically significant impact on local control. Our study demonstrates that patients with LABC and IBC treated with trimodality therapy can achieve excellent local control rates. Increased chest wall doses and mastectomy scar boosts are not necessary to achieve excellent rates of local control. This is clinically relevant, especially in this era of increased combined breast reconstruction and post-mastectomy radiation therapy, whereby higher RT doses to the reconstructed chest wall can be avoided, thereby potentially reducing the rate of complications