The significance of tumor budding in T1 colorectal carcinoma: the most reliable predictor of lymph node metastasis especially in endoscopically resected T1 colorectal carcinoma

Endoscopic resection is widely recognized as a first-line treatment for T1 colorectal cancers (CRC), although additional surgical intervention may be indicated based on the risk of lymph node (LN) metastasis. However, risk factors for LN metastasis in T1 CRC not fully established. We investigated the clinicopathological features of T1 CRC and evaluated their association with lymph node metastasis in 133 cases of T1 CRC, consisting of 87 cases with first-line endoscopic resection (EMR) followed by additional surgery and 46 cases with primary surgical resection. Among the total 133 cases, 16 cases (12.0%) showed LN metastasis; 13 cases (13/16, 81.25%) were included in endoscopic resection cohort. These were all of the non-pedunculated gross type and most of LN+ tumors invaded submucosa over 1000 μm (surgical cohort versus endoscopic resection cohort; 3 versus 11). However, there was no statistical difference in the depth of submucosal invasion between the LN+ and LN− in both surgical cohort (2799.42 μm ± 401.56 versus 3000.00 μm ± 721.69, P = .897) and endoscopic resection cohort (2066.55 μm ± 142.96 versus 2305.77 μm ± 345.62, P = .520). Conversely, presence of and a higher number of tumor budding foci were associated with an increase in the incidence of LN metastasis in both cohort (P < .0001). Positive resection margins as well as absence of adenoma component were also an independent predictive factor for lymph node metastasis in 87 cases with first-line endoscopic resection followed by additional surgery. We found that tumor budding was the most reliable LN metastasis predictor in T1 CRC in both surgically resected and endoscopic resection specimens.