Dosimetric Analysis of Cardiopulmonary Toxicity Treated With Definitive Chemoradiotherapy Using Volumetric Modulated Arc Therapy for Carcinoma of the Thoracic Esophagus

Background Volumetric modulated arc therapy (VMAT) has the ability to reduce monitor units and treatment time when compared with conventional intensity-modulated radiation therapy (IMRT) and is becoming the main irradiation method for IMRT. For thoracic esophageal cancer, there is concern about increased cardiopulmonary toxicities due to the increased volume of lung and heart irradiated to low doses. This retrospective study is to evaluate the safety of definitive chemoradiotherapy (dCRT) using VMAT for thoracic esophageal cancer. Methods Twenty patients with thoracic esophageal cancer treated with dCRT using VMAT from October 2019 to February 2022 at our institution were enrolled in this study. Median age was 61 years, male/female was 13/7, primary site was upper thoracic/middle thoracic/lower thoracic/upper-lower thoracic in 5/10/4/1, clinical stage was I/II/III/IV in 5/2/4/9, combination chemotherapy was platinum-based, and prescribed dose was 60 Gy/30 fractions in 19 patients, 50.4 Gy/28 fractions in 1 patient. Eleven patients overlapping head and neck cancers treated simultaneously. We evaluated the dosimetric parameters of lung and heart and the development of cardiopulmonary toxicities. Results Median lung volume receiving 20 Gy dose (V20), volume receiving 15 Gy dose (V15), volume receiving 5 Gy dose (V5) was 11.7 (1.5–22.3) %, 21.3 (4.3–34.8) %, and 65.6 (29.2–98.4) %, respectively and median mean lung dose was 10.0 (4.1–13.7) Gy. Median heart volume receiving 30 Gy dose (V30) was 31.2 (2.7–77.1) % and median mean heart dose was 25.9 (1.3–41.1) Gy. Regarding cardiopulmonary toxicities above grade 2, grade 2 pneumonia was observed in 1 patient, and grade 2 pericardial effusion was observed in 1 patient, with no grade 3 or higher with median follow-up period from start of radiotherapy was 22.5 (1.3–59.3) months. Conclusion No severe lung adverse events were observed in patients of thoracic esophageal cancer treated with dCRT using VMAT by keeping the mean lung dose below 15 Gy and lung V20 below 23%.