RAS, BRAF, and TP53 gene mutations in Taiwanese colorectal cancer patients.

Background: Colorectal cancer (CRC) plays an important role in cancer mortality and morbidity. This study examined colorectal tissues for RAS, BRAF, and TP53 gene mutations to assess their value as indicators of outcomes of CRC therapy.

Material and methods: DNA was extracted from tissues taken from 165 patients with CRC. RAS gene mutations (exons 2 and 3) were detected by primer extension analysis. BRAF gene mutations (V600E) were detected by high resolution melting (HRM) analysis. TP53 gene mutations (exons 5-8) were detected by direct sequencing.

Results: RAS, BRAF, and TP53 mutations occurred in 36.97% (61/165), 4.24% (7/165), and 37.58% (62/165), respectively. The KRAS mutation is a predictor for poor 5-year survival (p = 0.05), and the co-presence of KRAS and TP53 mutations correlates with lymph node involvement (p = 0.029), tumor stage (p = 0.029), and poor survival (p = 0.021). Multivariate analysis adjusted for tumor size, histologic grade, lymph node metastasis, sex, and age also indicated that KRAS mutations correlate significantly with overall survival (p = 0.036).

Conclusion: The KRAS mutation is not present in about one-third of CRC patients, and therefore other gene mutations need to be investigated to better understand the molecular mechanisms of CRC and its treatment.