Whole Breast Radiotherapy in the Lateral Isocentric Lateral Decubitus Position: Long-term Efficacy and Toxicity Results

Purpose: To evaluate previously published whole breast radiotherapy (WBRT) using ILD (isocentring lateral decubitus) technique in terms of toxicity and efficacy. Materials and methods: From 2006 to 2010, 832 female patients with early-stage breast cancer (BC) treated by conservative surgery underwent 3D-conformal WBRT-ILD at Institut Curie. The acute toxicity of treatment was evaluated weekly and the late toxicity (6 months and later after the treatment) was evaluated every 6 months till the 5th year after the end of the radiotherapy using NCI CTC v3.0 scale. Dosimetric study was performed to analyse the mean cardiac dose and the mean homolateral and contralateral lung doses. Results: The median follow up was 6.4 years. The median age was 61.5 years (range, 29-90), and median body mass index (BMI) was 26.3. Fifty one percent of the patients presented left sided BC and 49% right sided. Different type of fractions were used: 46.5% of pts.: 50 (breast) + 16 Gy (boost) in 33 fractions (fr), in 17.9%-50 Gy/25 fr, in 26.1%-40/15 fr or 41.6 GO 3 fr and in 9.5%: 30 Gy/5 fr. Acute dermatitis was present in 93% with a median of apparition of 4 weeks, and only 2,8% grade 3. In multivariate analysis, the cup size had significant influence (p = 0.0004) and the fractionation had a significative influence (p = 0.0001). In the all patients' population, 94.1% of cases had no skin toxicity at 1 year. No cardiac or pulmonary toxicity was reported. The median overall survival had not been reached at the end of follow-up. We observed 36 (3.6%) recurrences, as following: 30 local (breast) recurrences, 4 lymph node (LN), and 2 pts experiencing both. Conclusion: Whole breast radiotherapy in the lateral decubitus position provides excellent results in terms of local control and survival. ILD is well tolerated with very good acute toxicity profile. No cardiac or pulmonary toxicity were observed in this study. Longer follow-up is needed to confirm these results. (C) 2017 Elsevier B.V. All rights reserved.