Metabolic liver cancer: associations of rare and common germline variants in one-carbon metabolism and DNA methylation genes

Animal studies implicate one-carbon metabolism and DNA methylation genes in hepatocellular carcinoma (HCC) development in the setting of metabolic perturbations. Using human samples, we investigated the associations between common and rare variants in these closely related biochemical pathways and risk for metabolic HCC development in a multicenter international study. We performed targeted exome sequencing of 64 genes among 556 metabolic HCC cases and 643 cancer-free controls with metabolic conditions. Multivariable logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for multiple comparisons. Gene-burden tests were used for rare variant associations. Analyses were performed in the overall sample and among non-Hispanic whites. The results show that among non-Hispanic whites, presence of rare functional variants in ABCC2 was associated with 7-fold higher risk of metabolic HCC (OR = 6.92, 95% CI: 2.38-20.15, P = 0.0004), and this association remained significant when analyses were restricted to functional rare variants observed in ≥2 participants (cases 3.2% versus controls 0.0%, P = 1.02 × 10-5). In the overall multiethnic sample, presence of rare functional variants in ABCC2 was nominally associated with metabolic HCC (OR = 3.60, 95% CI: 1.52-8.58, P = 0.004), with similar nominal association when analyses were restricted to functional rare variants observed in ≥2 participants (cases 2.9% versus controls 0.2%, P = 0.006). A common variant in PNPLA3 (rs738409[G]) was associated with higher HCC risk in the overall sample (P = 6.36 × 10-6) and in non-Hispanic whites (P = 0.0002). Our findings indicate that rare functional variants in ABCC2 are associated with susceptibility to metabolic HCC in non-Hispanic whites. PNPLA3-rs738409 is also associated with metabolic HCC risk.

Metabolic Risk Factors for Hepatocellular Carcinoma in Patients with Nonalcoholic Fatty Liver Disease: A Prospective Study

Non-alcoholic fatty liver disease (NAFLD) is a fast-growing public health problem and predisposes to hepatocellular carcinoma (HCC) in a significant proportion of patients. Metabolic alterations might underlie the progression of NAFLD to HCC, but the magnitudes of risk and population-attributable risk fractions (PAFs) for various metabolic conditions that are associated with HCC risk in patients with NAFLD are unknown. We investigated the associations between metabolic conditions and HCC development in individuals with a prior history of NAFLD. The study included 11,245 participants in the SEER-Medicare database, comprising 1310 NAFLD-related HCC cases and 9835 NAFLD controls. We excluded individuals with competing liver diseases (e.g., alcoholic liver disease and chronic viral hepatitis). Baseline pre-existing diabetes mellitus, dyslipidemia, obesity, hypertension, hypothyroidism, and metabolic syndrome were assessed. Multivariable-adjusted logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). PAFs were also calculated for each metabolic condition. The results show that diabetes (OR = 2.39, 95% CI: 2.04-2.79), metabolic syndrome (OR = 1.73, 95% CI: 1.49-2.01), and obesity (OR = 1.62, 95% CI: 1.43-1.85) were associated with a higher HCC risk in individuals with NAFLD. The highest PAF for HCC was observed for pre-existing diabetes (42.1%, 95% CI: 35.7-48.5), followed by metabolic syndrome (28.8%, 95% CI: 21.7-35.9) and obesity (13.2%, 95% CI: 9.6-16.8). The major predisposing factors for HCC in individuals with NAFLD are diabetes mellitus, metabolic syndrome, and obesity, and their control would be critically important in mitigating the rising incidence of NAFLD-related HCC.

Association of metabolic health phenotypes, obesity, and hepatocellular carcinoma risk

BACKGROUND

The obesity and hepatocellular carcinoma (HCC) risk association may differ by individuals' metabolic health status.

AIM

To investigate the association between obesity categories and HCC risk among individuals with different metabolic health phenotypes.

METHODS

A case-control study among 518 HCC cases and 1,036 frequency-matched controls was conducted. Body mass index (BMI) was assessed before diagnosis. Pre-diagnosis data on dyslipidemia, hypertension, and diabetes were used to categorize participants as metabolically healthy or metabolically unhealthy. Participants were further categorized into metabolically healthy normal weight (MHNW), metabolically healthy overweight (MHOW), metabolically healthy obese (MHO), metabolically unhealthy normal weight (MUNW), metabolically unhealthy overweight (MUOW), and metabolically unhealthy obese (MHO). We used logistic regression to calculate multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Being overweight (OR=1.68, 95%CI=1.21-2.34) or obese (OR=1.49, 95%CI=1.11-1.89) was associated with higher HCC risk. Among metabolically healthy participants, no association was found between being overweight or obese and HCC risk. However, among the metabolically unhealthy participants, being overweight (OR=1.89, 95%CI=1.31-2.72) or obese (OR=1.50, 95%CI=1.07-2.09) was associated with higher HCC risk. Compared to the MHNW phenotype, no association was found between the MHOW and MHO phenotypes and HCC risk, but the MUNW (OR=1.94, 95%CI=1.09-3.43), MUOW (OR=3.78, 95%CI=2.15-6.65), and MUO (OR=2.93, 95%CI=1.70-5.05) phenotypes were associated with higher HCC risk.

CONCLUSION

The association between BMI and HCC appears to be restricted to individuals with underlying metabolic abnormalities.

Hepatocellular Carcinoma Risk Prediction in the NIH-AARP Diet and Health Study Cohort: A Machine Learning Approach

BACKGROUND

Prediction of hepatocellular carcinoma (HCC) development in persons with known risk factors remain a challenge and is an urgent unmet need, considering projected increases in HCC incidence and mortality in the US. We aimed to use machine learning techniques to identify a set of demographic, lifestyle, and health history information that can be used simultaneously for population-level HCC risk prediction.

METHODS

Data from 377,065 participants of the NIH-AARP Diet and Health Study, among whom 647 developed HCC over 16 years of follow-up, were analyzed. The sample was randomly divided into independent training (60%) and validation (40%) sets. We evaluated 123 participant characteristics and tested 15 different machine learning algorithms for robustness in predicting HCC risk. Separately, we evaluated variables selected from multivariable logistic regression for risk prediction.

RESULTS

The random under-sampling boosting (RUSBoost) algorithm performed best during model testing. Fourteen participant characteristics were selected for risk prediction based on differences between cases and controls (Bonferroni-corrected p-values <0.0004) and from the most frequently used variables in the initial two decision trees of the RUSBoost learner trees. A predictive model based on the 14 variables had an AUC of 0.72 (sensitivity=0.68, specificity=0.63) and independent validation AUC of 0.65 (sensitivity=0.68, specificity=0.63). A subset of 9 variables identified through logistic regression also had an AUC of 0.72 (sensitivity=0.67, specificity=0.63) and independent validation AUC of 0.65 (sensitivity=0.70, specificity=0.61).

CONCLUSION

Population-level HCC risk prediction can be performed with a machine learning-based algorithm and could inform strategies for improving HCC risk reduction in at-risk groups.

Influence of Cancer Susceptibility Gene Mutations and ABO Blood Group of Pancreatic Cancer Probands on Concomitant Risk to First-Degree Relatives

BACKGROUND

ABO blood group is associated with pancreatic cancer risk. Whether ABO blood group alone or when combined with inherited mutation status of index pancreatic cancer cases (probands) can enhance pancreatic cancer risk estimation in first-degree relatives (FDR) is unclear. We examined FDRs' risk for pancreatic cancer based on probands' ABO blood group and probands' cancer susceptibility gene mutation status.

METHODS

Data on 23,739 FDRs, identified through 3,268 pancreatic cancer probands, were analyzed. Probands' ABO blood groups were determined serologically or genetically, and 20 cancer susceptibility genes were used to classify probands as "mutation-positive" or "mutation-negative." SIRs and 95% confidence intervals (CI) were calculated, comparing observed pancreatic cancer cases in the FDRs with the number expected in SEER-21 (reference population).

RESULTS

Overall, FDRs had 2-fold risk of pancreatic cancer (SIR = 2.00; 95% CI = 1.79-2.22). Pancreatic cancer risk was higher in FDRs of mutation-positive (SIR = 3.80; 95% CI = 2.81-5.02) than mutation-negative (SIR = 1.79; 95% CI = 1.57-2.04) probands (P < 0.001). The magnitude of risk did not differ by ABO blood group alone (SIR_{blood-group-O} = 1.57; 95% CI = 1.20-2.03, SIR_non-O = 1.83; 95% CI = 1.53-2.17; P = 0.33). Among FDRs of probands with non-O blood group, pancreatic cancer risk was higher in FDRs of mutation-positive (SIR = 3.98; 95% CI = 2.62-5.80) than mutation-negative (SIR = 1.66; 95% CI = 1.35-2.03) probands (P < 0.001), but risk magnitudes were statistically similar when probands had blood group O (SIR_{mutation-positive} = 2.65; 95% CI = 1.09-5.47, SIR_{mutation-negative} = 1.48; 95% CI = 1.06-5.47; P = 0.16).

CONCLUSIONS

There is a range of pancreatic cancer risk to FDRs according to probands' germline mutation status and ABO blood group, ranging from 1.48 for FDRs of probands with blood group O and mutation-negative to 3.98 for FDRs of probands with non-O blood group and mutation-positive.

IMPACT

Combined ABO blood group and germline mutation status of probands can inform pancreatic cancer risk estimation in FDRs.

Shorter Treatment-Naïve Leukocyte Telomere Length is Associated with Poorer Overall Survival of Patients with Pancreatic Ductal Adenocarcinoma

BACKGROUND

Critically shortened telomeres contribute to chromosomal instability and neoplastic transformation and are associated with early death of patients with certain cancer types. Shorter leukocyte telomere length (LTL) has been associated with higher risk for pancreatic ductal adenocarcinoma (PDAC) and might be associated also with survival of patients with PDAC. We investigated the association between treatment-naïve LTL and overall survival of patients with incident PDAC.

METHODS

The study included 642 consecutively enrolled PDAC patients in the Mayo Clinic Biospecimen Resource for Pancreas Research. Blood samples were obtained at the time of diagnosis, before the start of cancer treatment, from which LTL was assayed by qRT-PCR. LTL was first modeled as a continuous variable (per-interquartile range decrease in LTL) and then as a categorized variable (short, medium, long). Multivariable-adjusted HRs and 95% confidence intervals (CI) were calculated for overall mortality using Cox proportional hazard models.

RESULTS

Shorter treatment-naïve LTL was associated with higher mortality among patients with PDAC (HR_continuous = 1.13, 95% CI: 1.01-1.28, P = 0.03; HR_{shortest vs. longest LTL} = 1.29, 95% CI: 1.05-1.59, P _trend = 0.01). There was a difference in the association between LTL and overall mortality by tumor stage at diagnosis; resectable tumors (HR_continuous = 0.91; 95% CI: 0.73-1.12), locally advanced tumors (HR_continuous = 1.29; 95% CI: 1.07-1.56), and metastatic tumors (HR_continuous = 1.17; 95% CI: 0.96-1.42), P _interaction = 0.04.

CONCLUSION

Shorter treatment-naïve LTL is associated with poorer overall survival of patients with incident PDAC.

IMPACT

Peripheral blood LTL might be a prognostic marker for PDAC.

One-carbon metabolism-related micronutrients intake and risk for hepatocellular carcinoma: A prospective cohort study

Deficient intake of micronutrients involved in one-carbon metabolism (eg, choline, methionine, vitamin B₁₂ and folic acid) leads to hepatocellular carcinoma (HCC) development in rodents, but is under-investigated in humans. We investigated the association between one-carbon metabolism-related micronutrient intake and HCC risk in a prospective cohort of 494 860 participants with 16 years of follow-up in the NIH-AARP study. Dietary intakes and supplement use were ascertained at baseline using a food-frequency questionnaire. Total intake (diet plus supplements) of the following one-carbon metabolism-related micronutrients were calculated: folate, methionine and vitamins B₂ (riboflavin), B₃ (niacin), B₆ and B₁₂ . These micronutrients were examined both individually and simultaneously, with adjustment for covariates. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Over the 16-year follow-up period, 647 incident HCC cases were diagnosed. When examined individually, higher total vitamin B₃ intake was associated with a lower HCC risk (HR_{Q5 vs Q1} = 0.60; 95% CI = 0.42-0.85; P_trend = .008), and the association remained significant when all six micronutrients were examined simultaneously (HR_{Q5 vs Q1} = 0.32; 95% CI = 0.18-0.55; P_trend < .0001). Among participants with >3 years of follow-up, higher total vitamin B₃ intake was again associated with lower risk (HR_{Q5 vs Q1} = 0.37; 95% CI = 0.20-0.68; P_trend = .001), whereas higher total vitamin B₆ intake was associated with higher risk (HR_{Q5 vs Q1} = 2.04; 95% CI = 1.02-4.07; P_trend = .04). Restricted cubic spline analyses showed a dose-response inverse association between total vitamin B₃ intake and HCC risk, and dose-response positive association between total vitamin B₆ intake and HCC risk. The study suggests that higher vitamin B₃ intake is associated with lower HCC risk, whereas higher vitamin B₆ intake is associated with increased risk.

Leukocyte Telomere Length and Its Interaction with Germline Variation in Telomere-Related Genes in Relation to Pancreatic Adenocarcinoma Risk

BACKGROUND

Leukocyte telomere length (LTL) has been associated with risk of multiple cancers, but its association with pancreatic ductal adenocarcinoma (PDAC) is unclear. We therefore investigated the association between peripheral blood LTL and PDAC risk, and examined effect modification by candidate SNPs previously reported to be associated with variation in LTL.

METHODS

A case-control study of 1,460 PDAC cases and 1,459 frequency-matched controls was performed using biospecimens and data from the Mayo Clinic Biospecimen Resource for Pancreas Research. Quantitative PCR was used to measure LTL and categorized into tertiles based on sex-specific control distribution. Eleven telomere-related SNPs also were genotyped. Logistic regression was used to calculate ORs and 95% confidence intervals (CI).

RESULTS

Shorter peripheral blood LTL was associated with a higher risk of PDAC (OR_T1vsT3 = 1.26, 95% CI = 1.03-1.54, P _trend = 0.02; OR_continuous = 1.14, 95% CI = 1.02-1.28), but the association was restricted to cases with treatment-naïve blood samples (OR_T1vsT3 = 1.51, 95% CI = 1.16-1.96, P _trend = 0.002; OR_continuous = 1.25, 95% CI = 1.08-1.45) and not cases whose blood samples were collected after initiation of cancer therapy (OR_T1vsT3 = 1.10, 95% CI = 0.87-1.39, P _trend = 0.42; OR_continuous = 1.08, 95% CI = 0.94-1.23). Three SNPs (TERC-rs10936599, ACYP2-rs11125529, and TERC-rs1317082) were each associated with interindividual variation in LTL among controls, but there was no evidence of effect modification by these SNPs.

CONCLUSIONS

Treatment-naïve short LTL is associated with a higher risk of PDAC, and the association does not differ by germline variation in the candidate telomere-related SNPs examined.

IMPACT

Peripheral blood LTL might serve as a molecular marker for risk modeling to identify persons at high risk of PDAC.

Independent and Joint Use of Statins and Metformin by Elderly Patients With Diabetes and Overall Survival Following HCC Diagnosis

GOAL

To investigate associations of prediagnosis and postdiagnosis use of statins and metformin on overall survival of patients with diabetes who later developed HCC.

BACKGROUND

Statins and metformin have received considerable interest as potential chemopreventive agents against hepatocellular carcinoma (HCC) development in individuals with type 2 diabetes mellitus (T2DM); however, their impact on overall survival of patients with T2DM who later develop HCC (diabetic HCC patients) is unclear.

STUDY

Data on 2499 elderly diabetic HCC patients obtained from the SEER-Medicare program (2009 to 2013) were analyzed. Patients were categorized based on use of statins only, metformin only, both, or neither (reference for all comparisons). The patients were further categorized based on: (1) metformin dose: ≤1500 or >1500 mg/d; (2) statins functional form: hydrophilic (pravastatin and rosuvastatin) or lipophilic (atorvastatin, fluvastatin, lovastatin, and simvastatin); (3) statins potency: high (atorvastatin, rosuvastatin, and simvastatin) or low (fluvastatin, lovastatin, and pravastatin); and (4) individual statins type. Multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard models.

RESULTS

Prediagnosis use of metformin dose ≤1500 mg/d was associated with lower risk of death after HCC diagnosis in patients with T2DM (HR, 0.72; 95% CI, 0.58-0.91), adjusting for postdiagnosis metformin dose, diabetes severity, Charlson comorbidity index, tumor characteristics, and other relevant factors. No association was found for prediagnosis metformin dose >1500 mg/d or postdiagnosis metformin use. Further, no association was found for either prediagnosis or postdiagnosis statins use.

CONCLUSIONS

Prediagnosis use of metformin dose ≤1500 mg/d is associated with longer overall survival of elderly diabetic HCC patients.

Pancreatic cancer risk is modulated by inflammatory potential of diet and ABO genotype: a consortia-based evaluation and replication study

Diets with high inflammatory potential are suspected to increase risk for pancreatic cancer (PC). Using pooled analyses, we examined whether this association applies to populations from different geographic regions and population subgroups with varying risks for PC, including variation in ABO blood type. Data from six case-control studies (cases, n = 2414; controls, n = 4528) in the Pancreatic Cancer Case-Control Consortium (PanC4) were analyzed, followed by replication in five nested case-control studies (cases, n = 1268; controls, n = 4215) from the Pancreatic Cancer Cohort Consortium (PanScan). Two polymorphisms in the ABO locus (rs505922 and rs8176746) were used to infer participants' blood types. Dietary questionnaire-derived nutrient/food intake was used to compute energy-adjusted dietary inflammatory index (E-DII®) scores to assess inflammatory potential of diet. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable-adjusted logistic regression. Higher E-DII scores, reflecting greater inflammatory potential of diet, were associated with increased PC risk in PanC4 [ORQ5 versus Q1=2.20, 95% confidence interval (CI) = 1.85-2.61, Ptrend < 0.0001; ORcontinuous = 1.20, 95% CI = 1.17-1.24], and PanScan (ORQ5 versus Q1 = 1.23, 95% CI = 0.92-1.66, Ptrend = 0.008; ORcontinuous = 1.09, 95% CI = 1.02-1.15). As expected, genotype-derived non-O blood type was associated with increased PC risk in both the PanC4 and PanScan studies. Stratified analyses of associations between E-DII quintiles and PC by genotype-derived ABO blood type did not show interaction by blood type (Pinteraction = 0.10 in PanC4 and Pinteraction=0.13 in PanScan). The results show that consuming a pro-inflammatory diet and carrying non-O blood type are each individually, but not interactively, associated with increased PC risk.

Risk of De Novo Hepatocellular Carcinoma Following Use of Direct Acting Antiviral Medications for Treatment of Chronic Hepatitis C

Direct-acting antivirals (DAA) are now the mainstay of treatment for patients with chronic hepatitis C virus (HCV); however, there is some controversy over whether use of DAAs for HCV, as compared with IFN-based regimens, leads to an increased risk for hepatocellular carcinoma (HCC) development. We investigated the association between use of DAAs and subsequent development of HCC in longitudinal data from patients with HCV from diverse backgrounds (various ages, ethnicities, and geographic regions) across the United States. The design was a retrospective study performed using medical and pharmacy claims from OptumLabs. HCV treatment exposure was categorized as DAA-only, DAA + IFN, any-DAA, or IFN-only. To account for confounding by indication, inverse probability of treatment weighting was performed. Cox proportional hazard models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI). We identified 5,781 patients with HCV with no history of HCC at baseline. Compared with IFN-only regimen, no significant increase in HCC risk was found for use of DAA-only (HR, 1.53; 95% CI, 0.73-3.23), DAA + IFN (HR, 1.02; 95% CI, 0.51-2.06), or any-DAA (HR, 1.04; 95% CI, 0.65-1.65). When stratified by sustained virological response (SVR), we noted a higher HCC risk for DAA-only among patients who achieved SVR post-treatment (HR, 7.53; 95% CI, 1.48-38.34), but the CIs were wide, which might be due to the small sample size of the subgroups. Among those who did not achieve SVR, no association was found for use of DAA-only (HR, 0.59; 95% CI, 0.19-1.91). These findings do not provide compelling evidence for the conception that use of DAAs for HCV is associated with increased risk of HCC development.

Leukocyte Telomere Length and Pancreatic Cancer Risk: Updated Epidemiologic Review

Many risk factors have been firmly established for pancreatic cancer (PC), but the molecular processes by which known risk factors influence susceptibility to PC are not clear. There has been a recent upsurge of interest in the role of telomere length (TL), the protective DNA sequence repeats at chromosome ends, in pancreatic carcinogenesis. Given this heightened interest, we performed an in-depth, focused, and up-to-date review of the epidemiological evidence linking leukocyte TL (LTL) with PC risk. We searched MEDLINE, Embase, and the Cochrane Library databases for all published studies on LTL and PC risk, up to May 2017. Five studies were identified for review: 4 nested case-control studies and 1 retrospective case-control study. Two studies found opposite associations between LTL and PC risk: 1 found a dose-response positive association and the other found a dose-response inverse association. Two studies also found a "U-shaped" association, whereas another reported a weak nonlinear relationship. We offer potential reasons for the conflicting findings including variation in study design, biospecimen characteristics, and differences in interlaboratory measurements of TL. Future studies should carefully control for risk factors of PC that are associated also with telomere attrition and investigate the role of genetic variation in TL maintenance.