Analysis of factors influencing molecular testing at diagnostic of colorectal cancer

Background The aim of the study was to evaluate the current rate of molecular testing prescription ( KRAS codons 12/13, BRAF and microsatellite instability (MSI)) in newly diagnosed colorectal cancer (CRC) patients and to determine which factors influence testing. Methods All incident CRC cases in 2010 were identified in the Poitou-Charentes General Cancer Registry. The exhaustive molecular testing performed was accessed in the French molecular genetics platform. Factors influencing prescription were analyzed using logistic regression. Results Among the 1269 CRCs included in the study, KRAS , BRAF and MSI testing accounted for 35.1%, 10.5% and 10.9%, respectively. KRAS testing was carried out in 65.5% of metastatic CRCs, and 26.1% of non-metastatic CRCs. Among metastatic CRCs, age (<60 years), site of primary tumour (left colon) and geographical area of treatment were factors related to KRAS testing. BRAF testing was contemporary to KRAS testing for 92.5% of patients. Factors related to MSI testing were age (<60 years), TNM stage (stage IV) and geographical area of treatment. Among CRC patients under 60 years old, only 37.5% had MSI testing. Conclusion These results underscore the need to reduce disparities in CRC molecular testing and highlight the limited application of the French guidelines, especially concerning MSI testing.