This is a study protocol details a randomized trial taking place in Thailand with multiple centers comparing IMPT and IMRT for stage II–IVA squamous thoracic esophageal cancer. This study is designed to demonstrate the clinical benefit of IMPT in esophageal cancer treatment in terms of survival and toxicity outcomes. A total of 232 patients will be randomized to receive IMPT or IMRT using a 1:1 allocation ratio, with the study timeframe of 2021 to 2026. IMPT is set for 50 Gy RBE in 25 fractions followed by a shrinking field boost of 10–14 Gy in 5–7 fractions to the high-risk volume, whereas IMRT for 50–50.4 Gy in 25–28 fractions, given 1.8–2 Gy daily fraction, allowing SIB technique to give higher radiation up to 54 Gy to high-risk volume.