KRAS status and metastasis prognosis
LUNG METASTASIS, REGRESSION, METASTASIS, LIVER METASTASIS
To investigate the prognostic value of KRAS in our cohort, we explored the association of KRAS status with post-treatment metastasis, including metastasis to the lung, liver, bone, abdominal lymph nodes and peritoneum. The diagnosis of lung metastasis was made from thorax contrast-enhanced computed tomography (CT), which was performed at each follow-up. Liver metastasis was detected first by abdominal CT at each follow-up and further diagnosed by abdominal contrast-enhanced CT or liver MRI. Bone metastasis was diagnosed by CT, MRI or positron emission computed tomography, which was performed when the patients developed local symptoms. Abdominal lymph node and peritoneal metastasis were defined on abdominal CT or MRI.To further explore if a significant association with lung metastasis existed, we conducted Cox regression and Kaplan‒Meier survival analyses, in which significance was detected by the log-rank test. Metastasis-free survival was defined as the time from TME to the first confirmation of metastasis or the last follow-up in patients alive and free from metastasis. The patients were recommended to be followed up every 3 months within the first 2 years after TME, every 6 months within the next 3–5 years and every 1 year thereafter.