Hypofractionated post mastectomy radiotherapy (PMRT) is commonly given using conventional radiotherapy technique. Volumetric modulated arc therapy (VMAT) and Intensity modulated radiation therapy (IMRT) are better sparing heart and lungs. This study was conducted to assess the toxicity profile and dosimetry outcomes of patients receiving PMRT using IMRT or VMAT.
67 biopsy-proven patients with carcinoma of the breast who had undergone modified radical mastectomy (MRM) were included in the study. They were treated using VMAT or IMRT to a dose of 42.56 Gy in 16 fractions. Acute and late toxicities were graded using RTOG toxicity grading scale. Toxicities and recurrences were summarized as proportions with 95% confidence intervals. Spearman’s correlation was used to find association between the dose received by the organs at risk (OARs) and the grade of toxicities.
The mean age of the study population was 48±9.5 years. The incidence of acute grade 2 and above radiation dermatitis and pneumonitis were 11.9% and 7.5 % respectively. The incidence of acute esophagitis was 46.3%. With a median follow up of 9 months there were no significant late toxicities. There was only one local recurrence and three progressed to distant metastases but without local recurrence. Twenty-four patients were treated by IMRT, 43 patients were treated by VMAT. Dosimetrically VMAT and IMRT were comparable in planning target volume (PTV) coverage and OAR doses, but VMAT had less number of monitor units and shorter treatment time.