Diabetes mellitus in relation to colorectal tumor molecular subtypes: A pooled analysis of more than 9000 cases

Folate intake and colorectal cancer risk according to genetic subtypes defined by targeted tumor sequencing

BACKGROUND

Folate is involved in multiple genetic, epigenetic, and metabolic processes, and inadequate folate intake has been associated with an increased risk of cancer.

OBJECTIVE

We examined whether folate intake is differentially associated with colorectal cancer (CRC) risk according to somatic mutations in genes linked to CRC using targeted sequencing.

DESIGN

Participants within 2 large CRC consortia with available information on dietary folate, supplemental folic acid, and total folate intake were included. Colorectal tumor samples from cases were sequenced for the presence of nonsilent mutations in 105 genes and 6 signaling pathways (IGF2/PI3K, MMR, RTK/RAS, TGF-β, WNT, and TP53/ATM). Multinomial logistic regression models were analyzed comparing mutated/nonmutated CRC cases to controls to compute multivariable-adjusted odds ratios (ORs) with 95% confidence interval (CI). Heterogeneity of associations of mutated compared with nonmutated CRC cases was tested in case-only analyses using logistic regression. Analyses were performed separately in hypermutated and nonhypermutated tumors, because they exhibit different clinical behaviors.

RESULTS

We included 4339 CRC cases (702 hypermutated tumors, 16.2%) and 11,767 controls. Total folate intake was inversely associated with CRC risk (OR = 0.93; 95% CI: 0.90, 0.96). Among hypermutated tumors, 12 genes (AXIN2, B2M, BCOR, CHD1, DOCK3, FBLN2, MAP3K21, POLD1, RYR1, TET2, UTP20, and ZNF521) showed nominal statistical significance (P < 0.05) for heterogeneity by mutation status, but none remained significant after multiple testing correction. Among these genetic subtypes, the associations between folate variables and CRC were mostly inverse or toward the null, except for tumors mutated for DOCK3 (supplemental folic acid), CHD1 (total folate), and ZNF521 (dietary folate) that showed positive associations. We did not observe differential associations in analyses among nonhypermutated tumors, or according to the signaling pathways.

CONCLUSIONS

Folate intake was not differentially associated with CRC risk according to mutations in the genes explored. The nominally significant differential mutation effects observed in a few genes warrants further investigation.

Prognostic Impact of Type 2 Diabetes in Metastatic Colorectal Cancer

Background Diabetes mellitus (DM) is a prognostic factor for some malignancies, but its clinical implications in metastatic colorectal cancer (mCRC) patients are less clear. Therefore, we conducted a retrospective study to evaluate the impact of pre-existing type 2 diabetes mellitus (T2DM) on the survival outcomes of patients with newly diagnosed mCRC. Methodology We retrospectively included patients with newly diagnosed mCRC between January 2017 and June 2021 and with pre-existing T2DM. Data on the characteristics of patients, clinicopathological features, and drug exposure were collected from the electronic medical records. The primary endpoint was overall survival (OS). Secondary endpoints were progression-free survival (PFS) and treatment-related adverse events (TRAEs). Results Among 187 mCRC patients, 54 (28.8%) had T2DM. The median follow-up was 25 months. We observed 150 OS events and 168 PFS events. Diabetes significantly and negatively impacted PFS and OS. The median for PFS (mPFS) was eight and 16 months for T2DM and no T2DM patients, respectively (p < 0.0001; log-rank test). The median overall survival (mOS) was 15 and 29 months for T2DM and no T2DM patients, respectively (p < 0.0001; log-rank test). Patients with diabetes were more often overweight or obese (59.3% vs. 24.8%; p < 0.01) and had a poorer performance status (53.7% vs. 21.1% with Eastern Cooperative Oncology Group Performance Status 1; p < 0.01). Additionally, T2DM patients had more high-risk pathological features, including G3 grading tumors (27.7% vs. 12.0%; p = 0.01), lymph node involvement (p < 0.01), BRAF-mutated (35.1% vs. 6.8%; p < 0.01), and right-sided CRC (63.0% vs. 30.1%; p < 0.01). We found no statistically significant differences in TRAEs. Nevertheless, a significantly higher rate of grade 2-4 peripheral neuropathy (22.2% vs. 5.3%; p < 0.01) was reported in T2DM patients. Conclusions T2DM is a negative prognostic factor for survival in mCRC. The paper provides empirical evidence in favor of the joint control of both pathologies. Further research is needed to establish the robustness of our results.