Effects of Radiation Dose on Liver After Free-breathing Volumetric Modulated Arc Therapy for Breast Cancer

Abstract

Background/Aim: To evaluate the early effect of radiation dose on liver function in breast cancer patients undergoing free-breathing volumetric modulated arc therapy (FB-VMAT). Patients and Methods: Medical records of 125 patients with breast cancer who underwent curative surgery followed by postoperative radiotherapy using FB-VMAT during 2018-2021 were reviewed. Results of the liver function test (LFT), performed within 1-week before and 6 months after radiotherapy, were collected and compared. The LFTs analyzed albumin, total and direct bilirubin, aspartate transaminase, alanine transferase, and alkaline phosphatase levels. The mean dose and relative liver volume receiving at least 10 Gy, 20 Gy, or 30 Gy were calculated. Results: Median follow-up time was 21.4 months. One patient experienced locoregional and distant failures. The mean liver irradiation dose was 325.9 centigray (cGy) for all patients. The liver irradiation dose was higher in patients with right breast cancer than in those with left breast cancer (mean, 434.1 cGy vs. 260.6 cGy, p<0.001). Direct bilirubin and aspartate transaminase levels showed significant differences after FB-VMAT. LFT results outside normal limits were noted in 31 patients at follow-up, but nobody met the criteria of radiation-induced liver disease. Underlying liver disease, breast laterality, systemic treatment, or dose volume histogram parameters were not associated with abnormal LFT results. Conclusion: FB-VMAT can deliver radiation doses safely without adversely affecting the liver. The mean dose <= 4 Gy could be a useful dose criterium of the liver for FB-VMAT plans.