Study setting
The present study is a parallel-group, multicenter, superiority, randomized, phase II trial. The participants will be enrolled in nine tertiary academic hospitals in South Korea. The trial flow scheme is presented in Fig. 
Flowchart of the SOLAR trial. SCRT, short-course radiotherapy; FOLFOX, 5-fluorouracil with oxaliplatin; CRT, chemoradiotherapy; CT, computed tomography; MRI, magnetic resonance imaging; TME, total mesorectal excision