Clinical effects of accelerated partial breast irradiation using three-dimensional conformal radiotherapy in patients with early breast cancer after breast-conserving therapy

Objective: To assess the clinical effects of accelerated partial breast irradiation (APBI) using three-dimensional conformal radiotherapy (3DCRT) in patients with low-risk early breast cancer after breast-conserving therapy (BCT) with respect to dosimetric parameters, local control, toxicities, and cosmetic outcome. Methods: Thirty-nine patients with early breast cancer (stage 0-1) were enrolled in a prospective phase II trial of APBI using 3DCRT in 2008-2010. Of all the patients, 28 had invasive ductal carcinoma, 5 had ductal carcinoma in situ, and 6 had other types of invasive carcinoma. The prescribed dose was 38.5 Gy/10 fractions twice daily, with an inter-fraction interval greater than 6 h. The toxicities were assessed according to the National Cancer Institute Common Toxicity Criteria, version 3.0. The cosmetic outcome was assessed according to the Harris breast cosmesis scale. Results: The planning target volume coverage and normal-tissue dosimetry were appropriate in the APBI using 3DCRT. Dose homogeneity without deviation was achieved in 33 patients (85%). Of the total 39 patients, 46% met ASTROS 'cautionary' criteria, and 18% met 'unsuitable' criteria; also, 31% met GEC-ESTRO's 'intermediate-risk' criteria, and 3% met 'high-risk' criteria. The follow-up rate was 100%. No patient experienced local recurrence, and no grade 3-4 toxicities were found. Cosmesis was good to excellent in 35 patients (90%) at 6 months after APBI. Conclusions: The patients with early breast cancer after BCT are properly selected for APBI using 3DCRT, with satisfactory preliminary assessment results for local control, toxicities, and cosmetic outcome. (authors)