Retrospective accuracy analysis of major guidelines and factors for lymph node metastasis of pT1 colorectal cancer.

Background and study aims: The aim of this study was to validation the accuracy of major guidelines and their adopted unfavorable histologic factors for lymph node metastasis (LNM) in pT1 colorectal cancer (CRC). National Comprehensive Cancer Network (NCCN), Japanese Society for Cancer of the Colon and Rectum (JSCCR), European Society for Medical Oncology (ESMO), and French Intergroup Clinical Practice Guidelines (FICPG) were included. Patients and methods: Retrospectively, 519 cases receiving oncological resection with lymphadenectomy were included. Factors and four pathological parameters--histological differentiation grades (HDG), lymphovascular invasion (LVI), depth of submucosal invasion (DSI)(>1000μm), and tumor budding (TB)--were analyzed for their impact on LNM incidence individually and in combination as defined by the guidelines. Results: HDG, LVI, TB, and gender (female) are risk factors for LNM in multivariate analysis. All guidelines have significant ability to predict LNM ( P <0.001). NCCN and ESMO have similar performance, in terms of sensitivity (63.8%/68.1%) and specificity (62.7%/69.5%). JSCCR and FICPG had similar performance in terms of good sensitivity (100%/100%) and low specificity (25.6%/25.2%). The JSCCR/FICPG group had higher sensitivity and lower specificity and accuracy than the NCCN/ESMO group. Conclusions: HDG, LVI, TB, and gender (female) are independent risk factors for LNM of T1 CRC. DSI is an excellent negative predictor, although not an independent risk factor. The NCCN/ESMO guideline has medium sensitivity and requires improvement. The JSCCR/FICPG guideline has perfect sensitivity but low specificity, thus exposing patients to many unnecessary surgeries. There is revision potential for current guideline factors, including those beyond current pathological ones, to improve LNM prediction accuracy.