Comparison of different treatment planning methods used in esophageal cancer radiotherapy

The aims of this study are to make a dosimetric comparison of treatment plans prepared by using 3D Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) techniques on the planing computed tomography images of the patients with esophageal cancer and to determine which technique is more advantageous in routine clinical practice. Ten patients with middle thoracic esophageal cancer who received preoperative chemoradiotherapy at Ege University Faculty of Medicine Department of Radiation Oncology between 2010-2018 were included in this study. 4-field 3D-CRT, 4-field IMRT (IMRT-4F), 9-field IMRT (IMRT-9F) and double-ark VMAT (VMAT-2x) treatment planning techniques were compared dosimetrically for each patient. The comparisons were evaluated in terms of mean lung dose (Dmean), lung volume receiving 5, 10, 18, 20, and 30 Gy (V5, V10, V18, V20, and V30) mean heart dose (Dmean), heart volume receiving 35, and 40 Gy (V35, and V40), and maximum spinal cord dose (Dmax). As a result of the data obtained 3D-CRT technique was significantly superior in terms of mean lung dose, V5, and V10, and VMAT-2x technique was superior in terms of V18 (p=0.003, p=0.000, p=0.000, and p=0.011, respectively). Although VMAT-2x technique was superior in terms of lung V20, and V30 the difference was not statistically significant (p=0.197, and p=0.339, respectively). For the heart VMAT-2x technique was significantly superior for V35, and V40, (p=0.000, and p=0.004, respectively). Although VMAT-2x technique was superior regarding mean heart dose the difference was not statistically significant (p=0.241). 3D-CRT technique seemed superior in terms of maximum spinal cord dose however the difference was not significant (p=0.178). VMAT-2x technique was superior regarding the mean PTV dose (p=0.008), 3D-CRT was significantly superior regarding the conformity number (CN), and homogeneity index (HI) (p=0.029, and p=0.000, respectively). According to these results 3D-CRT was superior in terms of mean lung dose, lung V5, lung V10, CN and HI while VMAT-2x technique superior in terms of lung V18, heart V35, and V40, and mean PTV dose in the radiotherapy planning of middle thoracic esophageal cancer. Nevertheless in clinical pratice it is appropriate to consider the avantages and disadvantages of both techniques on the basis of the localization and size of the tumor, and lymph node involvement of each patient.