Tanabe T, et al. - As inguinal lymph nodes are classified as regional lymph nodes for anal canal carcinoma but non-regional lymph nodes for rectal carcinoma by the 8th edition of the tumor-node-metastasis classification and the different prognosis of inguinal lymph node metastasis from anal canal carcinoma and rectal carcinoma might be reflected by this difference, therefore, researchers analyzed consecutive patients (n = 31) with rectal or anal canal adenocarcinoma who underwent inguinal lymph node dissection with curative intent, focusing on the long-term consequences of inguinal lymph node metastasis from rectal or anal canal adenocarcinoma. According to the findings, there was no prognostic value of the location of primary tumor (rectum vs anal canal) whereas lateral lymph node metastasis and histological findings were identified as independent prognostic factors in multivariate analyses. Given the good prognosis, inguinal lymph node metastasis seemed to be regional rather than distant in patients with rectal or anal canal adenocarcinoma. For these patients, inguinal lymph node dissection may be indicated if R0 resection can be achieved.