Association between mutational subgroups, Warburg-subtypes, and survival in patients with colorectal cancer

Abstract

Background: Previous research suggests that Warburg-subtypes are related to potentially important survival differences in colorectal cancer (CRC) patients. In the present study, we investigated whether mutational subgroups based on somatic mutations in RAS, BRAF, PIK3CA, and MET, which are known to promote the Warburg-effect, as well as mismatch repair (MMR) status, hold prognostic value in CRC. In addition, we investigated whether Warburg-subtypes provide additional prognostic information, independent of known prognostic factors like TNM stage.

Methods: CRC patients (n = 2344) from the prospective Netherlands Cohort Study (NLCS) were classified into eight mutually exclusive mutational subgroups, based on observed mutations in RAS, BRAF, PIK3CA, and MET, and MMR status: All-wild-type + MMR_proficient , KRAS_mut + MMR_proficient , KRAS_mut + PIK3CA_mut + MMR_proficient , PIK3CA_mut + MMR_proficient , BRAF_mut + MMR_proficient , BRAF_mut + MMR_deficient , other + MMR_proficient , and other + MMR_deficient . Kaplan-Meier curves and Cox regression models were used to investigate associations between mutational subgroups and survival, as well as associations between our previously established Warburg-subtypes and survival within these mutational subgroups.

Results: Compared to patients with all-wild-type + MMR_proficient CRC, patients with KRAS_mut + MMR_proficient , KRAS_mut + PIK3CA_mut + MMR_proficient , BRAF_mut + MMR_proficient , or other + MMR_proficient CRC had a statistically significant worse survival (HR_CRC-specific ranged from 1.29 to 1.88). In contrast, patients with other + MMR_deficient CRC had the most favorable survival (HR_CRC-specific 0.48). No statistically significant survival differences were observed for the Warburg-subtypes within mutational subgroups.

Conclusion: Our results highlight the prognostic potential of mutational subgroups in CRC. Warburg-subtypes did not provide additional prognostic information within these mutational subgroups. Future larger-scale prospective studies are necessary to validate our findings and to examine the potential clinical utility of CRC subtyping based on mutational subgroups.

Keywords: Warburg-effect; colorectal cancer; oncogenes; prognosis; survival.

FIGURE 1

Flow diagram of the number of CRC patients available for analyses in the Netherlands Cohort Study (NLCS), 1986–2006. CRC, colorectal cancer; PALGA, Netherlands pathology database; TMA, tissue microarray.

FIGURE 2

Mutation frequencies and established mutational subgroups of 2344 CRC patients within the Netherlands Cohort Study (NLCS, 1986–2006). (A) Multi‐layered pie chart showing the distribution and frequencies of genetic alterations in KRAS, PIK3CA, BRAF, NRAS, and MET, as well as single‐, double‐, and triple‐mutations in combination with MMR status. The inner circle shows the total mutation frequencies of KRAS, PIK3CA, BRAF, NRAS, and MET. The outer circle shows single‐ double‐ and triple‐ mutations which together contribute to the total mutation frequency, in combination with MMR status. Mutations with a frequency ≤1.2% are not shown. Note: Percentages do not add up to 100% because there is some degree of overlap between mutational groups (e.g., KRAS + PIK3CA). Image colon: Flaticon.com. (B) Pie chart showing the distribution and frequencies of the eight established mutational subgroups: All‐wild‐type + pMMR, KRAS _mut  + pMMR, KRAS _mut  + PIK3CA _mut  + pMMR, PIK3CA _mut  + pMMR, BRAF _mut  + pMMR, BRAF _mut  + dMMR, other+pMMR, and other + dMMR. (C) Histogram showing the distributions and frequencies of combinations of markers (mutational status and MMR status) that together make up the other + dMMR subgroup. (D) Histogram showing the distribution and frequencies of combinations of markers (i.e., mutational status and MMR status) that together make up the other + pMMR subgroup.

FIGURE 3

Kaplan–Meier curves according to mutational subgroups (i.e., all‐wild‐type + pMMR, KRAS _mut  + pMMR, KRAS _mut  + PIK3CA _mut  + pMMR, PIK3CA _mut  + pMMR, BRAF _mut  + pMMR, BRAF _mut  + dMMR, other+pMMR, and other+dMMR) in colorectal cancer patients within the Netherlands Cohort Study (NLCS, 1986–2006), showing (A) CRC‐specific survival (median survival times: KRAS _mut  + pMMR, 7.16 years and BRAF _mut  + pMMR, 2.48 years) and (B) overall survival (median survival times: All‐wild‐type + pMMR, 5.73 years; KRAS _mut  + pMMR, 3.49 years; KRAS _mut  + PIK3CA _mut  + pMMR, 4.79 years; PIK3CA _mut  + pMMR, 5.91 years; BRAF _mut  + pMMR, 1.83 years; BRAF _mut  + dMMR, 5.46 years; other + pMMR, 4.25 years; other + dMMR, 8.04 years).