Patients
cancer, Cancer
TUMOURS, CANCER, RECTAL ADENOCARCINOMA, ONCOLOGY, CANCER
This retrospective multicentre study was conducted at two tertiary academic cancer institutions in China and was approved by the ethics committees of Peking University Cancer Hospital and Institute, the leading site. Participants signed informed consent forms before the study began.From January 2012 to January 2019, 103 LARC patients were identified. The inclusion criteria were as follows: (1) histologically confirmed rectal adenocarcinoma; (2) stage cT3-4N0M0 or cTxN + M0 (AJCC 8th) confirmed by MRI; (3) standard concurrent neoadjuvant chemoradiotherapy followed by TME; (4) available KRAS mutation status; (5) available MRI images (T2-weighted imaging, T2WI) before neoadjuvant therapy with sufficient image quality; (6) age ≥ 18 years; and (7) Eastern Cooperative Oncology Group (ECOG) score < 2. Eventually, we included 103 LARC patients and randomly divided the patients into training and testing cohorts at a 7:3 ratio, which was 73 and 30 patients, respectively.The patients’ baseline characteristics were obtained from medical records. The neoadjuvant concurrent chemoradiotherapy strategy was long-course radiation (22–25 fractions of 2–2.3 Gy for primary rectal tumours, with 1.8–2 Gy to the clinical target volume that included the mesorectal area, internal iliac, obturator, and presacral lymphatic drainage area) with concurrent capecitabine 825 mg/m