Development of a risk-scoring system to evaluate the serosal invasion for macroscopic serosal invasion positive gastric cancer patients.

BACKGROUND: The status of serosal invasion is often discordance between pathological and intraoperative evaluation. Our study sought to develop a risk-scoring system (RSS) to predict the probability of pT4a for macroscopic serosal invasion (MSI) positive patients and reevaluate the serosal invasion status.

PATIENTS AND METHODS: A total of 1301 pT3/pT4a gastric cancer patients with curative surgery were reviewed. We constructed the RSS to predict the probability of pT4a and assigned MSI-positive patients into different risk groups based on the risk scores. The prognostic significance of these risk groups was also evaluated.

RESULTS: Univariate and multivariate analyses identified that tumor location, Lauren type, Borrmann type, tumor size, lymphovascular invasion and pN stage were risk factors related to pT4a. Survival analyses showed that pT3 MSI-positive patients in high-risk group had similar survival with pT4a patients. We incorporated these two groups into one stage and proposed a novel revised-T stage. Two-step multivariate analyses indicated that the revised-T stage showed better prediction ability for prognosis and peritoneal recurrence assessment than original pT stage and MSI status.

CONCLUSIONS: In our present study, we developed a RSS to predict the probability of pT4a for MSI-positive patients. Based on our RSS, we proposed a treatment algorithm to reevaluate the tumor invasion for MSI-positive patients in clinical practice. Future studies should include other preoperative predictors to improve the clinical utility of our model.