Severe tumor budding is a risk factor for lateral lymph node metastasis in early rectal cancers

Lateral lymph node (LLN) metastasis sometimes occurs in patients with early rectal cancer that has invaded the submucosa (SM) and muscularis propria (MP). This study aims to identify the risk factor(s) for LLN metastasis in such patients.

We retrospectively analyzed 65 patients with pathological SM or MP lower rectal adenocarcinoma, for whom radical resection had been performed at a single institution.

We performed LLN dissection in 52 (80%) patients. The LLN dissection rates in the case of pathological SM and MP tumors were 65.6% and 94.4%, respectively, and the corresponding LLN metastasis rates were 6.9% and 11.1%. Severe tumor budding was found to be a risk factor for LLN metastasis (P = 0.002). Further, of six patients with LLN metastasis, four did not have coincident mesenteric lymph node metastasis.

In rectal cancer that has pathologically invaded SM and MP, LLN metastasis is not negligible. LLN dissection could lower the local recurrence rate of SM and MP rectal cancer. In case LLN dissection is not performed, patients with a high tumor budding grade should be administered adjuvant therapy.