Validation of microsatellite instability histology scores with Bethesda guidelines in hereditary nonpolyposis colorectal cancer.

AIMS: Hereditary nonpolyposis colorectal cancer (HNPCC) is a subgroup of colorectal cancer (CRC) which should be differentiated because of the high risk for additional cancers and risk evaluation for other family members, especially for CRC. It is not practical to perform genetic testing for all CRC patients; therefore, various prediction modalities, for example, Bethesda guideline (BG) were studied in the literature. We aimed to assess the association of microsatellite instability (MSI), histology scores, and BG for predicting HNPCC risk.

SUBJECTS AND METHODS: Data were collected from CRC patients between 2009 and 2012. A total of 127 patients were retrospectively reviewed for BG status and the MSI scores, MsPath, and PathScore.

STATISTICAL ANALYSIS USED: Definitive statistical methods (mean, standard deviation, median, frequency, and percentage) were used to evaluate the study data. Comparison used Student's t-test, Continuity (Yates) correction, Fisher-Freeman-Halton test, Pearson correlation, and receiver operating characteristics curve analysis.

RESULTS: Patients who were detected as Bethesda-positive had significantly higher MsPath and PathScore scores (P = 0.001 and P = 0.007, respectively). According to the cut-off value of 2.8 and 2.9 for MsPath and PathScore, respectively, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 90%, 43%, 22.8%, 95.8%, and 50.4% for MsPath, and 55%, 83.2%, 37.9%, 90.8%, and 78.7% for PathScore, respectively.

CONCLUSIONS: The MSI scoring systems, MsPath, and PathScore, are reliable systems and effectively correlated with BG for predicting patients who need advanced analysis techniques because of the risk of HNPCC.