Results of a clinical phase II trial of whole breast irradiation with a hypofractionated simultaneous integrated boost to the tumor bed after breast-conserving surgery for early breast cancer

Abstract

Objective To report the clinical results of whole breast irradiation with a hypofractionated simultaneous integrated boost to the tumor bed after breast-conserving surgery for early breast cancer. Methods From October 2010 to April 2013, 200 patients with early breast cancer who were admitted to our center and treated with breast-conserving surgery were prospectively enrolled as subjects. All patients received inversely intensity-modulated whole breast irradiation with a dose of 45 Gy in 25 fractions and a simultaneous integrated boost to the tumor bed with a dose of 0.6 Gy/Fx (a total dose of 60 Gy in 25 fractions) five times a week. Logistic regression analysis was used to examine the predictive factors for the occurrence of grade 2 radiation skin reactions. Results All patients completed the radiotherapy treatment. The mean planning target volumes (PTVs) of diseased breast and tumor bed were 529.2 cc and 92.9 cc, respectively. The mean V20 of the ipsilateral lung was 17.2%, and the mean dose for the heart was 531 cGy in patients with left breast cancer. According to the Common Terminology Criteria for Adverse Events, version 3.0, the incidence rates of grade 0, 1, and 2 radiation dermatitis in all patients were 8%, 63%, and 29%, respectively. In all patients, 10.5% had moist desquamation. The multivariate analysis revealed that the PTVs of the tumor bed and whole breast were predictive factors for grade 2 dermatitis. In 185 patients who did self-evaluation of breast cosmetic outcome, 50(87.1%) were rated as excellent, 111(60.0%) as good, and 24(12.9%) as fair. The median follow-up time was 38 months (2-56 months), and the 3-year local control rate was 98.7%. Conclusions The whole breast irradiation with a hypofractionated simultaneous integrated boost to the tumor bed achieves satisfactory acute skin toxicity profile and cosmetic outcome. A 3-year follow-up reveals a good local control rate. Key words: Breast neoplasms/conservative surgery; Breast neoplasms/radiotherapy; Radiotherapy, simultaneously integrated boost; Treatmeng outcome