Risk Factors for Nodal Involvement in Early-Stage Rectal Cancer: a New Scoring System Based on the Analysis of 326 Cases.

BACKGROUND: the purpose of this study was to identify which clinicopathological features of early-stage rectal cancer (ESRC) are significantly correlated with the risk of local-regional lymph node metastases (LNM) and to quantify the strength of this association through a novel scoring system. According to several case studies, about 20% of operated ESRC are found with occult lymph nodal metastases at the histological examination. The low frequency of local recurrence in these tumors treated with total mesorectal excision (TME) compared to transanal approaches highlights the role of mesorectal lymph nodes as a site of metastatic location. METHODS: Overall, 386 consecutive patients with ESRC treated with radical resection and TME were examined in a retrospective, observational multi-centric study, operated between 2007 and 2019 in seven centers. Demographic and tumor related clinicopathological characteristics were identified, collected and analyzed. Each variable was specifically weighted based on the strength of its association with the presence of nodal metastases. A scoring system using these weighted variables was developed. RESULTS: Six variables were found to be significantly associated with local regional LNM: lymphatic invasion combined with vascular invasion, poor differentiation (G3), stage T2, age >= 60 years, male sex, perineural invasion. A novel scoring system weighted on the presence of each of these variables able to quantify the risk of LNM in ESRC was developed. CONCLUSIONS: The proposed scoring system is a good predictor of the risk of LNM and should be of help in the decision-making process for ESRC cases diagnosed either by local excision or endoscopic biopsy.