| Summary: | Study rationale: The coexistence of KRAS and PIK3CA mutations in cells implies potential synergistic hyperactivation of the Ras/MAPK and PI3K/Akt oncogenic pathways. Therefore, it is desirable to investigate the concomitant mutations of KRAS and PIK3CA in colorectal cancer (CRC) samples and whether the concomitant mutations are associated with a poor prognosis in CRC patients. Aim: To investigate the clinicpathological characteristics and prognostic value of concomitant mutations of KRAS and PIK3CA in CRC samples. Methods: In this study, a total of 655 CRC patients from the Sixth Affiliated Hospital of Sun Yat-sen University were enrolled from January to December 2015. Sanger sequencing was applied to survey the mutational status of hotspot regions in the open reading frames (ORFs) of the KRAS and PIK3CA genes. Clinicpathological parameters were collected and analyzed. The Kaplan-Meier method and Cox regression model were applied to determine the correlation between the KRAS and PIK3CA mutation statuses and survival. Results: We found that KRAS and PIK3CA bi-mutations were significantly associated with aggressive clinicpathological features. Among the studied CRC patients, those with either KRAS mutations (P = 0.004) or KRAS and PIK3CA bi-mutations (P = 0.033) had poor overall survival (OS). In the multivariable analysis, KRAS mutations in exons 3 and 4 but not exon 2 with concomitant PIK3CA mutations were associated with a high risk of death (univariate HR = 8.05; 95% CI, 1.926–33.64, P = 0.004; multivariate HR = 10.505; 95% CI, 2.304–47.905, P = 0.002). Conclusion: The concomitant mutation statuses of KRAS and PIK3CA should be considered when the prognostic value of gene mutations is consulted in CRC patients.
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