Development and Validation of a Predictive Score for Preoperative Detection of Lymphovascular Invasion in Rectal Cancer.

Background: Lymphovascular invasion (LVI) is an important prognosticator in rectal cancer (RC). We aimed to determine predictors for LVI in RC and incorporate them into a predictive risk score (PRS).

Methods: Case-control analysis of predictors of LVI in RC using data from a national database (2010-2019). Main outcome was LVI in RC and its predictors. Odds ratios of significant independent predictors of LVI were incorporated into a PRS.

Results: 55,178 patients were included (60.9% male; mean age: 61.3 years). LVI was detected in 10,446 (18.9%). Independent predictors were carcinomas that were signet-ring cell (OR: 1.98, p < 0.001), moderately differentiated (OR: 1.58, p < 0.001), poorly differentiated (OR: 3.9, p < 0.001), or undifferentiated carcinomas (OR: 4.1, p < 0.001), cN1 (OR: 1.21, p < 0.001), and cN2 (OR: 1.49, p < 0.001), stage and incorporated into a PRS (0-8). Incidence of LVI was 16.3% in the low-risk group, 27.8% in the intermediate-risk group, and 40.5% in the high-risk group (p < 0.001). The PPV of the score was 40.5%, NPV was 83.7%, accuracy was 82.4%, and specificity was 97.9%.

Conclusions: High-grade adenocarcinomas, signet-ring cell carcinomas, and lymph node involvement in clinical assessment were independently associated with LVI in RC. Incorporation of these predictors into a PRS conferred high specificity and good accuracy.