Pulsed reduced dose rate for re-irradiation of recurrent breast cancer.Pract Radiat Oncol 2019PR
Locoregionally recurrent breast cancer within a previously irradiated field requires weighing the benefits of re-irradiation must be weighed against the increased rates of toxicity. Here we evaluate the outcomes of patients treated with pulsed reduced dose rate (PRDR) radiation therapy with concurrent low dose capecitabine as a method to increase the therapeutic ratio of retreatment.
Patients treated from 11/00/2000 to 06/01/2018 with PRDR radiation therapy at XXXX were identified. Patients were retreated to a median dose of 54 Gy (range 37.5-66 Gy) using PRDR radiation therapy, delivering radiation at an apparent dose rate of 6.67 cGy/min to allow for increased sublethal damage repair of normal tissues. The median cumulative dose was 109.8 Gy. Twenty-two patients were treated with concurrent capecitabine, most frequently at 500mg BID. The Kaplan-Meier method was used for survival analysis and Cox regression analysis was used for univariate and multivariate analysis.
Forty-three patients were identified who underwent re-irradiation for locoregionally recurrent invasive breast cancer with a median follow-up of 20.5 months. Twenty-four patients had gross disease. Nineteen patients had simultaneous metastatic disease. The complete response rate was 83.3% in patients treated with gross disease. Locoregional recurrence free survival was 81.3% and 73.8% for all patients at one and two years, respectively. Overall survival for patients with localized disease was 95.7% at one year and 91.1% at two years. The rate of acute grade 3 radiation dermatitis was 25.6% with no other acute grade 3 toxicities. Grade 3 late toxicity occurred in 18.6% of patients.
PRDR radiation therapy with capecitabine were well tolerated and effective method for treating patients with recurrent breast cancer. Prospective studies are necessary to compare side effects and efficacy with conventional dose rate re-irradiation, as well as, to evaluate the potential role for capecitabine in the recurrent setting.