KRAS Mutation: Characterization and Its Impact on Survival Outcome of Patients with Metastatic Colorectal Cancer.

Introduction: Colorectal cancer (CRC) is one of the most common cancer types, with rising incidence due to imbalanced lifestyle and dietary habit. Association between CRC cases and mutation has been established recently. Brunei Darussalam, located within the Borneo island, is of diverse ethnicity which could represent the genome of Southeast Asia population. Our study, for the first time, determined the survival outcome of metastatic colorectal cancer (mCRC) and established the link with mutation by modelling the population in Brunei Darussalam.

Methods: We collected data of 76 metastatic CRC (mCRC) patients undergoing treatment at The Brunei Cancer Centre, the national centre for cancer treatment in Brunei. These patients were diagnosed with Stage 4 CRC between 1 January 2013 and 31 December 2017. Age, gender, ethnicity, date of diagnosis, site of primary tumour, metastatic sites and molecular analysis of mutation status (either mutated or wild-type) of tumour were recorded. The survival outcomes of these mCRC patients were analysed.

Results: The end of this study period recorded 73.1% deceased mutant mCRC patients and 46.0% deceased wild-type mCRC patients, contributing to death rates of 45.2% and 54.8%, correspondingly. Chi-squared analysis showed a significant difference between the survival outcomes of wild-type and mutant mCRC patients (-value = 0.024).

Conclusions: There is a significant difference between the survival outcomes of wild-type and mutant mCRC patients in the Brunei population. In addition, we found that mutations in codon 12 of gene on mutant mCRC patients have shorter survival median periods than those with mutations within codon 13 of gene. This is the first study in Brunei Darussalam to analyse both the survival outcomes of mCRC patients and those of mutant mCRC patients.