The Value Of Contrast-enhanced CT In Assessing Microsatellite Instability In Colorectal Cancer

Objectives: To evaluate the predictive value of contrast-enhanced computed tomography(CT)in assessing microsatellite instability(MSI)and prognosis in patients with colorectal cancer(CRC).Methods: The preoperative contrast-enhanced CT images and medical records of CRC patients from March 2010 to March 2016 were collected and retrospectively reviewed.Patients were randomly divided into the training set and validation set in a1:1 ratio.CT images were analyzed,including tumor location,the ratio of low-density area,enhancement degree,enhancement pattern,and intestinal wall thickening pattern.Univariable and multivariable logistic regression analyses were performed to assess the relationship between all variables and MSI.Areas under the curve(AUC)were used to estimate the predictive performance of variables.Survival analyses were performed using the Kaplan-Meier method.Results: Of the 382 CRC cases patients enrolled,MSI was identified in 40(10.5%)patients,and microsatellite stability(MSS)was identified in 342(89.5%)patients.In the univariable logistic regression analysis,tumor location,the ratio of low-density area,enhancement degree,and enhancement pattern showed significant differences between the MSI group and the MSS group in CRC(all P < 0.05).In the multivariable logistic regression analysis,the tumor location [left-side location group vs right-side location group,odd ratio(OR)0.21,95% confidence interval(95% CI)0.06-0.61,P = 0.005,in the training set;OR 0.27,95% CI 0.08-0.84,P = 0.02,in the validation set] and the ratio of low-density area(the ratio of low-density area is greater than 2/3 vs the ratio of lowdensity area is less than 1/3,OR 10.6,95% CI 2.87-39.5,P < 0.001,in the training set;OR 5.75,95% CI 1.69-19.8,P = 0.005,in the validation set)maintained significant differences between the MSI group and MSS group.The AUC value of the combination of tumor location and ratio of low-density area was 0.80(95% CI 0.70-0.90)in the training set and 0.75(95% CI 0.63-0.87)in the validation set.In the left-side location group,the 5-year overall survival of the low ratio of low-density area group and the high ratio of low-density area group was 75.7%,56.2%,respectively(P = 0.004).Conclusion: The model combined ratio of low-density area and tumor location can help assess MSI status and the prognosis in patients with CRC prior to surgery.