Table 1 The inclusion and exclusion criteria

Inclusion criteria:

•Age (years): 18–75

•Histologically confirmed rectal cancer

•Clinical stage: cTxN1-2M0 or cT3-4N0M0

•Suspicion of LLN metastasis: short-axis diameter of lateral lymph nodes (LLN) >5 mm; short diameter of common iliac or external iliac lymph nodes >6 mm [16, 24, 25]

•No extramesorectal lymph node swelling (short-axis diameter <10 mm)

•No invasion of other organs

•Performance Status (PS): 0, 1

•No past history of chemotherapy, pelvic surgery, or radiation

•Written informed consent operative criteria:

•Mesorectal excision is performed

•Operative findings:

Main lesion of the tumor is located at the rectum

Lower tumor margin is below the peritoneal reflection

Stage R0 after resection

Exclusion criteria:

•High rectal cancer: lower tumor margin is above the peritoneal reflection

•Multiple-cancer patients

•Pregnant patients

•Patients with psychological disorder

•Steroid administration

•Cardiac infarction within previous 6 months

•Severe pulmonary emphysema and/or pulmonary fibrosis

•Physician’s decision to exclude

•Patients with confirmed LLN metastasis: short-axis diameter of LLN >10 mm and a lymph node with an irregular edge, heterogeneous signal, or obvious enlargement and after nCRT has been completed, lymph node enlarges more than 30%

•Emergency surgery

•Patients with coagulopathies