The critical role of tumor size in predicting lymph node metastasis in early-stage colorectal cancer

Background: Main purpose of this study is to investigate impact of tumor size on risk of lymph node metastasis (LNM) in pT1-stage colorectal cancer (CRC), focusing on colon, rectosigmoid junction, and rectum.

Method: Patients diagnosed with primary pT1 CRC between 2015 and 2019 were selected from National Cancer Database, utilizing International Classification of Diseases for Oncology, Third Edition (ICD-O-3) codes. We analyzed factors influencing LNM using uni- and multivariate analysis, then isolated tumor size to study its impact on LNM.

Results: In this study of 27,649 pT1-stage tumor patients, we found that 10 ​% of colon, 16 ​% of rectosigmoid junction, and 13 ​% of rectum were LNM+. The study had 14,339 males (51.97 ​%). Mean age was 64.9 (±11.7). In multivariate analysis, sample was adjusted by excluding confounding factors, isolating impact of tumor size on LNM. Analysis for only tumor size, patients with colon tumors >45 ​mm had 53 ​% increased odds of LNM (95 ​% CI [1.06, 2.23], p ​= ​0.03), whereas tumor size did not significantly affect LNM in rectosigmoid and rectum cases, with odds ratios of 2.05 (95 ​% CI [0.82, 5.09], p ​= ​0.12) and 1.62 (95 ​% CI [0.97, 2.71], p ​= ​0.065) respectively, for tumors ≥45 ​mm compared to those <15 ​mm.

Conclusion: This investigation refines predictors of LNM, crucial for tailoring organ-sparing strategies in early-stage CRC management. While tumor size is significant determinant of LNM in colon cancer, early rectal and rectosigmoid cancers may be associated with lower risk of LNM.