Radiation-induced lung and heart toxicity in patients with early-stage breast cancer treated with hypofractionated radiotherapy following breast-conservative surgery.

Abstract

73 Background: Hypofractionated RT for breast cancer (BC), although reducing cost and time, could have negative impact on normal underlying lung and heart. We studied and compared lung function and the post –RT radiological changes using High–Resolution CT (HRCT) in early BC patients, treated with 3-D conformal whole breast radiotherapy (WBRT) using either conventional or hypofractionated regime. Additionaly, in patients with right-sided breast cancer, we monitored changes in LVEF performing MUGA scans. Methods: Between 2008 and 2009, 61 early BC patients (TI-2N0M0) were randomised into Group A (n=31) and Group B (n=30) receiving standard radiotherapy with 50Gy/25f/5w plus boost 10Gy/5f/1w to tumour bed or 43.2Gy/16f/22d plus same boost dose respectively. All patients were subjected to dynamic lung testing, on D0 (before RT), during and after RT at 3 and 6 months. HRCT scans were performed at baseline, and 3, 6, 12 months after RT. Dosimetric factors (CLD, V20, D25, MLD) were calculated. MUGA was performed in patients with right sided BC prior and 6 and 12 months post RT. Results: At 3 months after RT, pulmonary changes were classified at HRCT as follows: 91.8% were Grade 0, 8.19% Grade 1, and 0% Grade 2. At 6 months, 86.98% were Grade 0, 11.47 % Grade 1, and 1.6% Grade 2. At 12 months, 88.52% were Grade 0, 9.19 % Grade 1 and 3.27% Grade 2. Univariate analysis showed strong association between radiation pneumonitis, age and all dosimetric parameters. There was no association between fractionation type and incidence of RN. FEV1, FVC, FEV 25, FEV 50 and DLCO showed no statistically significant reduction in both treatment groups in 3 and 6 months following RT, compared to baseline. Multivariate analysis showed no relation between HRCT findings and age, smoking, chemotherapy, hormonotherapy, V20. No changes were found in LVEF prior and 6 and 12 months post radiotherapy. Conclusions: Lung toxicity as assessed with HRCT and PFTs was minimal in both treatment arms and our results are in consistency with other published data. In our series, no significant changes were found in LVEF in both treatment arms.