Associations between Ileal Juice Bile Acids and Colorectal Advanced Adenoma

BACKGROUND

There is an urgent need to identify biomarkers for advanced adenoma, an important precursor of colorectal cancer (CRC). We aimed to determine alterations in ileal juice bile acids associated with colorectal advanced adenoma.

METHODS

We quantified a comprehensive panel of primary and secondary bile acids and their conjugates using an ultraperformance liquid chromatography triple-quadrupole mass spectrometric assay in ileal juice collected at colonoscopy from 46 study subjects (i.e., 14 biopsy-confirmed advanced adenomas and 32 controls free of adenoma or cancer). Using analysis of covariance (ANCOVA), we examined the differences in bile acid concentrations by disease status, adjusting for age, sex, body mass index, smoking status and type 2 diabetes.

RESULTS

The concentrations of hyodeoxycholic acid (HCA) species in ileal juice of the advanced adenoma patients (geometric mean = 4501.9 nM) were significantly higher than those of controls (geometric mean = 1292.3 nM, p = 0.001). The relative abundance of ursodeoxycholic acid (UDCA) in total bile acids was significantly reduced in cases than controls (0.73% in cases vs. 1.33% in controls; p = 0.046). No significant difference between cases and controls was observed for concentrations of total or specific primary bile acids (i.e., cholic acid (CA), chenodeoxycholic acid (CDCA) and their glycine- and taurine-conjugates) and total and specific major secondary bile acids (i.e., deoxycholic acid and lithocholic acid).

CONCLUSIONS

Colorectal advanced adenoma was associated with altered bile acids in ileal juice. The HCA species may promote the development of colorectal advanced adenoma, whereas gut microbiota responsible for the conversion of CDCA to UDCA may protect against it. Our findings have important implications for the use of bile acids as biomarkers in early detection of colorectal cancer.

Abstract 3015: Soluble CD137 and risk of hepatocellular carcinoma: nested case-control studies in cohorts in Shanghai and Singapore

Background: Chronic inflammation plays a significant role in hepatocellular carcinoma (HCC). With rising incidence and poor prognosis of HCC, identifying relatively less invasive biomarkers, especially inflammatory ones, may improve the assessment and stratification of HCC risk. The objective of our studies was to assess if CD8+ T cell cytokines in pre-diagnostic serum are associated with risk of HCC development.

Methods: We conducted two parallel case-control studies of HCC nested within the Shanghai Cohort Study (SCS) and the Singapore Chinese Health Study (SCHS), two prospective cohorts of 81,000 individuals with 25+ years of follow-up. The serum concentrations of five CD8+ T cell cytokines ─ soluble CD137 (sCD137), soluble Fas (sFas), perforin, macrophage inflammatory protein 1-beta (MIP-1β), and tumor necrosis factor alpha (TNF-α) ─ were determined using Luminex bead-based immunoassay on 315 HCC cases and 315 individually matched controls in the SCS, and on 197 HCC case-control pairs in the SCHS. Conditional logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (CI) for HCC with elevated levels of cytokines with adjustment for body mass index, alcohol drinking, cigarette smoking, seropositivity of hepatitis surface antigen (HBsAg), and history of diabetes.

Results: sCD137 levels were statistically significantly higher in HCC cases than controls in both cohorts. Compared with the 1st quartile (Q1) of sCD137, multivariable-adjusted ORs (95% CI) of HCC for the 4th quartile (Q4) were 3.8 (1.7-8.3) in the SCS and 3.5 (1.4 -8.5) in the SCHS (both Ptrend’s < 0.001). Among HBsAg-negative individuals, ORs (95% CIs) for Q2, Q3, & Q4 of sCD137 were 2.7 (1.5-4.9), 2.7 (1.4-5.0), and 4.5 (2.4-8.5), respectively, compared with Q1 (Ptrend < 0.001) in both SCS and SCHS combined. The corresponding ORs (95% CIs) among HBsAg- positive individuals were 21.0 (9.3-47.6), 34.1 (13.8-84.2), and 56.7 (23.3-137.9), respectively, with a P=0.095 for multiplicative interaction. The sCD137-HCC risk association remained constant over different time periods from blood draw to HCC diagnosis: ORs (95% CIs) for Q4 vs. Q1 were 4.7 (1.2-17.5) for <5 years, 3.7 (1.3-10.6) for 5-10 years, and 3.94 (1.6-9.5) for more than 10 years between blood collection and cancer diagnosis. sFas was positively associated with HCC risk in the SCHS but not in the SCS. There was no statistically significant association for perforin, MIP-1β, or TNF-α with HCC risk in either cohort.

Conclusion: These novel and validated findings demonstrated that serum sCD137 levels were significantly elevated many years prior to HCC diagnosis, and had a potential synergistic effect with chronic viral infection on the HCC risk. sCD137 may be developed as a immune monitoring biomarker for risk stratification and assessment, which can lead to early diagnosis and improve prognosis of HCC patients.

Citation Format: Claire E. Thomas, Jennifer J. Adibi, Allison L. Kuipers, Brenda Diergaarde, Hung N. Luu, Aizhen Jin, Woon-Puay Koh, Yu-Tang Gao, Jennifer Adams-Haduch, Renwei Wang, Anna Lokshin, Jaideep Behari, Jian-Min Yuan. Soluble CD137 and risk of hepatocellular carcinoma: nested case-control studies in cohorts in Shanghai and Singapore [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3015.

Soluble CD137 and risk of hepatocellular carcinoma: nested case-control studies in cohorts in Shanghai and Singapore

BACKGROUND

The majority of hepatocellular carcinoma (HCC) cases occur in the presence of cirrhosis. Biomarkers of cirrhosis-associated immune dysfunction such as CD8+ T cell cytokines could aid HCC risk assessment.

METHODS

CD8+ T cell cytokines were determined in pre-diagnostic serum in two studies including 315 HCC case-control pairs in the Shanghai Cohort Study (SCS) and 197 pairs in the Singapore Chinese Health Study (SCHS). Conditional logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (CI) for HCC with levels of five cytokines-soluble CD137 (sCD137), soluble Fas (sFas), perforin, macrophage inflammatory protein 1-beta (MIP-1β), and tumour necrosis factor alpha (TNF-α).

RESULTS

sCD137 levels were significantly higher in HCC cases than controls in both cohorts (Ps < 0.001). Compared with the lowest quartile, multivariable-adjusted ORs (95% CI) of HCC for the highest sCD137 quartile were 3.79 (1.73, 8.30) in the SCS and 3.49 (1.44, 8.48) in the SCHS. The sCD137-HCC association was independent of hepatitis B seropositivity and follow-up time. No other cytokine was consistently associated with HCC risk.

CONCLUSION

sCD137 was associated with higher risk of HCC in two studies nested in general population cohorts. sCD137 may be a long-term risk marker of HCC development.

Impact of Genetic Variants in the Nicotine Metabolism Pathway on Nicotine Metabolite Levels in Smokers

BACKGROUND

Nicotine metabolism is a major factor in nicotine dependence, with approximately 70% to 80% of nicotine metabolized to cotinine in Caucasians. Cotinine formation is catalyzed primarily by CYP2A6, which also converts cotinine to trans-3'-hydroxycotinine (3HC). The goal of the present study was to examine the effects of CYP2A6 deficiency on nicotine metabolism profiles in vivo and the importance of genetic variants in nicotine-metabolizing enzyme genes on urinary nicotine metabolites levels.

METHODS

Urine samples from 722 smokers who participated in the Singapore Chinese Health Study were analyzed using UPLC-MS/MS to detect nicotine and eight of its urinary metabolites, and a total of 58 variants in 12 genes involved in nicotine metabolism were investigated in 475 of these subjects with informative genotyping data.

RESULTS

Urine samples stratified by the ratio of 3HC/cotinine exhibited a 7-fold increase in nicotine-N'-oxide, a 6-fold increase in nicotine-Glucuronide (Gluc), and a 5-fold decrease in 3HC-Gluc when comparing the lower versus upper 3HC/cotinine ventiles. Significant (P < 0.0001) associations were observed between functional metabolizing enzyme genotypes and levels of various urinary nicotine metabolites, including CYP2A6 genotype and levels of nicotine, nicotine-Gluc, nicotine-N'-oxide and 3HC, UGT2B10 genotype and levels of cotinine, nicotine-Gluc and cotinine-Gluc, UGT2B17 genotype and levels of 3HC-Gluc, FMO3 genotype and levels of nicotine-N'-oxide, and CYP2B6 genotype and levels of nicotine-N'-oxide and 4-hydroxy-4-(3-pyridyl)-butanoic acid.

CONCLUSIONS

These data suggest that several pathways are important in nicotine metabolism.

IMPACT

Genotype differences in several nicotine-metabolizing enzyme pathways may potentially lead to differences in nicotine dependence and smoking behavior and cessation.

Serologic Profiling Using an Epstein-Barr Virus Mammalian Expression Library Identifies EBNA1 IgA as a Prediagnostic Marker for Nasopharyngeal Carcinoma

PURPOSE

The favorable prognosis of stage I and II nasopharyngeal carcinoma (NPC) has motivated a search for biomarkers for the early detection and risk assessment of Epstein-Barr virus (EBV)-associated NPC. Although EBV seropositivity is ubiquitous among adults, a spike in antibodies against select EBV proteins is a harbinger of NPC. A serologic survey would likely reveal which EBV antibodies could discriminate those at risk of developing NPC.

EXPERIMENTAL DESIGN

Lysates from a new EBV mammalian expression library were used in a denaturing multiplex immunoblot assay to survey antibodies against EBV in sera collected from healthy individuals who later developed NPC (incident cases) in a prospective cohort from Singapore and validated in an independent cohort from Shanghai, P.R. China.

RESULTS

We show that IgA against EBV nuclear antigen 1 (EBNA1) discriminated incident NPC cases from matched controls with 100% sensitivity and 100% specificity up to 4 years before diagnosis in both Singapore and Shanghai cohorts. Incident NPC cases had a greater IgG repertoire against lytic-classified EBV proteins, and the assortment of IgA against EBV proteins detected by the immunoblot assay increased closer to diagnosis.

CONCLUSIONS

Although NPC tumors consistently harbor latent EBV, the observed heightened systemic and mucosal immunity against lytic-classified antigens years prior to clinical diagnosis is consistent with enhanced lytic transcription. We conclude that an expanding EBV mucosal reservoir (which can be latent and/or lytic) is a risk factor for NPC. This presents an opportunity to identify those at risk of developing NPC using IgA against EBNA1 as a biomarker.

The Association between Serum Serine and Glycine and Related-Metabolites with Pancreatic Cancer in a Prospective Cohort Study

Background. Serine and glycine play an important role in the folate-dependent one-carbon metabolism. The metabolism of serine and glycine has been shown to be associated with cancer cell proliferation. No prior epidemiologic study has investigated the associations for serum levels of serine and glycine with pancreatic cancer risk. Methods. We conducted a nested case-control study involved 129 incident pancreatic cancer cases and 258 individually matched controls within a prospective cohort study of 18,244 male residents in Shanghai, China. Glycine and serine and related metabolites in pre-diagnostic serum were quantified using gas chromatography-tandem mass spectrometry. A conditional logistic regression method was used to evaluate the associations for serine, glycine, and related metabolites with pancreatic cancer risk with adjustment for potential confounders. Results: Odds ratios (95% confidence intervals) of pancreatic cancer for the highest quartile of serine and glycine were 0.33 (0.14−0.75) and 0.25 (0.11−0.58), respectively, compared with their respective lowest quartiles (both p’s < 0.01). No significant association with risk of pancreatic cancer was observed for other serine- or glycine related metabolites including cystathionine, cysteine, and sarcosine. Conclusion. The risk of pancreatic cancer was reduced by more than 70% in individuals with elevated levels of glycine and serine in serum collected, on average, more than 10 years prior to cancer diagnosis in a prospectively designed case-control study. These novel findings support a protective role of serine and glycine against the development of pancreatic cancer in humans that might have an implication for cancer prevention.

Abstract 748: Conjugated primary bile acids as a biomarker for hepatocellular carcinoma risk in two prospective cohorts

Background: Incidence rates of hepatocellular carcinoma (HCC) has been increasing for several decades in the U.S. Non-alcoholic liver disease (NAFLD) increasingly plays a role in the rising rate of HCC. Experimental data have shown that bile acids, which play key roles in the host-gut microbiota co-metabolism, contribute to the development of NAFLD and HCC. We propose to comprehensively examine the associations of bile acids with risk of HCC in two cohorts.

Methods: Thirty-five bile acids were quantified using the state-of-the-art ultraperformance liquid chromatography triple-quadrupole mass spectrometry assays in serum samples collected, on average, five years prior to diagnosis of 197 HCC and the same number of individually matched controls from the Singapore Chinese Health Study and the Shanghai Cohort Study. Conditional logistic regression was used to assess the associations for major bile acids and their conjugates, and bile acid ratios with the risk of HCC.

Results: Total primary bile acids were significantly elevated whereas the ratio of secondary bile acids over primary bile acids were significantly lower in HCC cases than controls in both cohorts (P's ≤ 0.001). Doubling of tauro- vs. glyco-conjugates of all bile acids, primary bile acids, and specifically chenodeoycholic acid resulted in an increase in HCC risk of 44, 48, and 34% (P = 0.004, &lt;0.001, 0.001) respectively after adjustment for potential confounders.

Conclusion: Primary bile acids, especially tauro-conjugated bile acids were strongly associated with increased risk of HCC risk whereas the secondary vs. primary bile acids ratios were associated with decreased risk of HCC.

Citation Format: Claire Elizabeth Thomas, Hung Luu, Renwei Wang, Guoxiang Xie, Jennifer Adams-Haduch, Aizhen Jin, Woon-Puay Koh, Wei Jia, Jaideep Behari, Jian-Min Yuan. Conjugated primary bile acids as a biomarker for hepatocellular carcinoma risk in two prospective cohorts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 748.

Low frequency variants associated with leukocyte telomere length in the Singapore Chinese population

The role of low frequency variants associated with telomere length homeostasis in chronic diseases and mortalities is relatively understudied in the East-Asian population. Here we evaluated low frequency variants, including 1,915,154 Asian specific variants, for leukocyte telomere length (LTL) associations among 25,533 Singapore Chinese samples. Three East Asian specific variants in/near POT1, TERF1 and STN1 genes are associated with LTL (Meta-analysis P 2.49×10-14-6.94×10-10). Rs79314063, a missense variant (p.Asp410His) at POT1, shows effect 5.3 fold higher and independent of a previous common index SNP. TERF1 (rs79617270) and STN1 (rs139620151) are linked to LTL-associated common index SNPs at these loci. Rs79617270 is associated with cancer mortality [HR95%CI = 1.544 (1.173, 2.032), PAdj = 0.018] and 4.76% of the association between the rs79617270 and colon cancer is mediated through LTL. Overall, genetically determined LTL is particularly associated with lung adenocarcinoma [HR95%CI = 1.123 (1.051, 1.201), Padj = 0.007]. Ethnicity-specific low frequency variants may affect LTL homeostasis and associate with certain cancers.

Serum IL27 in Relation to Risk of Hepatocellular Carcinoma in Two Nested Case-Control Studies

BACKGROUND

IL27 mRNA is highly enriched in the tissue of hepatocellular carcinoma. Overexpression of IL27 gene has been found to increase T-cell expression of inhibitory receptors, an immunosuppressive feature in tumor microenvironment, that promotes the development of hepatocellular carcinoma.

METHODS

Two parallel case-control studies of hepatocellular carcinoma, each with 100 case-control pairs were conducted in the Singapore Chinese Health Study and the Shanghai Cohort Study to examine the association between serum IL27 levels and risk of developing hepatocellular carcinoma.

RESULTS

The IL27 concentrations were significantly elevated in sera collected from study participants 4 to 5 years prior to the diagnosis of hepatocellular carcinoma in both cohort studies. Compared with the lowest tertile of IL27, odds ratios (OR) of hepatocellular carcinoma for the highest tertile of IL27 was 46.08 [95% confidence interval (CI), 4.68-453.86] in the Singapore Chinese Health Study and 19.09 (95% CI, 3.81-95.57) in the Shanghai Cohort Study (both P _trend <0.001). The corresponding ORs in both cohort studies were 42.47 (95% CI, 8.30-217.40) among individuals negative for hepatitis B surface antigen (HBsAg) and 242.46 (95% CI, 38.42-1,529.01) among those positive for HBsAg compared with the lowest tertile of interleukin-27 and negative HBsAg.

CONCLUSIONS

Levels of IL27 in prediagnostic sera were significantly associated with increased risk of hepatocellular carcinoma development.

IMPACT

IL27, through its immunosuppressive property, may play a significant role in the development of hepatocellular carcinoma. Serum levels of IL27 may be used as a biomarker for prediction of hepatocellular carcinoma development.

Abstract 4647: Diet quality indexes and risk of hepatocellular carcinoma: Findings from the Singapore Chinese Health Study

Background. There is a limited research on the association between combined dietary measures and liver cancer risk. We investigated the association between the four diet-quality index (DQI) scores, the Alternative Health Eating Index-2010 (AHEI-2010), Alternate Mediterranean Diet (aMED); Dietary Approaches to Stop Hypertension (DASH) and Heathy Diet Indicator (HDI) with liver cancer risk, using data from the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese men and women aged 45-74 at enrollment in 1993-1998 with up to 25 years of follow-up.

Methods. The Cox proportional hazard regression method was used to estimate hazard ratio (HR) and its 95% confidence interval (CI) of HCC with each DQI after adjustment for multiple potential confounders. The unconditional logistic regression method was used to evaluate the associations between the DQIs and HCC risk among a subset of individuals who tested negative for hepatitis B surface antigen (HBsAg).

Results. During an average 17.7 years of follow-up, 561 incident HCC cases were identified. High scores of AHEI-2010, aMED and DASH, representing higher dietary quality, were associated with lower risk of HCC (all Ptrend&lt;0.05). Compared with the lowest quartile, HRs (95% CIs) of HCC risk for the highest quartile of AHEI-2010, aMED and DASH were 0.71 (0.55-0.91), 0.73 (0.54-0.98), and 0.68 (0.52-0.89), respectively. These inverse associations were stronger in men than in women. No significant association between HDI and HCC risk was observed. Among HBsAg-negative individuals, similar inverse associations were observed, and the strongest inverse association was for aMED that reached statistically significance level (HRQ4vsQ1=0.48, 95% CI: 0.24-0.98).

Conclusion. Higher scores of AHED, aMED, and DASH were significantly associated with reduced risk of HCC in this Asian population. The findings support the notion that adherence to a healthier diet may lower the risk of HCC, suggesting that dietary modification may be an effective approach for primary prevention of HCC.

Funding: The Singapore Chinese Health Study was supported by the National Institutes of Health (NIH) of the United States (grants # R01 CA144034 and UM1 CA182876).

Citation Format: Hung N. Luu, Nithya Neelakantan, Ting-ting Geng, Renwei Wang, Jennifer Adams-Haduch, Aizhen Jin, Rob M. Van Dam, Woon-Puay Koh, Jian-Min Yuan. Diet quality indexes and risk of hepatocellular carcinoma: Findings from the Singapore Chinese Health Study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4647.

Abstract 4641: Association between dietary tomato intake and the risk of hepatocellular carcinoma: Findings from a prospective cohort study

Background: Intake of tomato and/or lycopene have been found to be associated with reduced risk of several cancer types, but epidemiological data on risk of hepatocellular carcinoma (HCC) are sparse.

Methods: The associations of tomato and lycopene consumption with risk of HCC were examined in the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese men and women aged 45-74 years at enrollment in 1993-1998 with 25 years of follow-up. Tomato and lycopene consumption was evaluated using a validated semi-quantitative food frequency questionnaire. Incident HCC cases were ascertained through the linkage analysis with the nationwide Singapore cancer registry. Cox proportional hazard regression was used to estimate hazard ratio (HR) and its 95% confidence interval (CI) of HCC with the consumption of tomato and lycopene among all cohort participants, and unconditional logistic regression was used to assess the association among individuals negative for hepatitis B surface antigen (HBsAg).

Results: After a mean follow-up of 17.6 years, 561 incident HCC cases were identified. Higher tomato intake was associated with lower risk of HCC after adjustment for multiple potential confounders (Ptrend&lt;0.001). Compared to the lowest quartile, HRs (95% CIs) of HCC for the 2nd, 3rd, and 4th quartile of tomato intake were 0.70 (0.56-0.88), 0.73 (0.58-0.92), and 0.63 (0.49-0.81). Among HBsAg-negative individuals, the inverse association remained (Ptrend=0.03). There was no association between lycopene intake and HCC risk (Ptrend=0.54).

Conclusion: Tomato intake may offer protection against the development of HCC, particularly among individuals without chronic infection with hepatitis B virus.

Citation Format: Claire E. Thomas, Hung N. Luu, Renwei Wang, Jennifer Adams-Haduch, Jian-Min Yuan, Aizhen Jin, Woon-Puay Koh. Association between dietary tomato intake and the risk of hepatocellular carcinoma: Findings from a prospective cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4641.

Abstract 2344: Composite score of healthy lifestyle factors and risk of hepatocellular carcinoma: Findings from a prospective cohort study

Background. While the associations between individual lifestyle factors and risk of hepatocellular carcinoma (HCC) were examined substantially, their combined impact on HCC risk has not been evaluated.

Methods. The association of a composite score of healthy lifestyle factors, including body mass index, alcohol consumption, cigarette smoking, alternative Mediterranean Diet (aMED), and sleep duration, with the risk of developing HCC was examined in the Singapore Chinese Health Study (SCHS), an on-going prospective cohort of 63,257 Chinese men and women aged 45-74 at enrollment in 1993-1998 with up to 25 years of follow-up. Cox proportional hazard regression method was used to estimate hazard ratio (HR) and its 95% confidence interval (CI) of HCC with the composite score after adjustment for multiple potential confounders. The unconditional logistic regression method was used to confirm the association between the composite lifestyle score and HCC risk among hepatitis B surface antigen (HBsAg) negative individuals to eliminate its potential confounding effect.

Results. After a mean follow-up of 17.7 years, 561 participants of the SCHS developed HCC. Individuals with higher composite scores, which represented for healthier lifestyles, were at significantly lower risk of HCC. Compared with the lowest composite score (i.e., 0-4), the HRs (95% CIs) for 5, 6, 7 and 8 were 0.48 (0.36-0.64), 0.44 (0.34-0.67), 0.37 (0.28-0.48), and 0.26 (0.17-0.39), respectively (Ptrend&lt;0.001). A similar inverse association was observed in participants with negative HBsAg serology; HR was 0.12 (95% CI: 0.04-0.38) for the highest versus the lowest category of the composite scores (Ptrend=0.01).

Conclusion. Healthy lifestyles are protective against the development of HCC, especially for individuals without viral infection. This finding highlights the importance of a comprehensive lifestyle modification strategy for primary prevention of HCC.

Funding: The Singapore Chinese Health Study was supported by the National Institutes of Health (NIH) of the United States (grants # R01 CA144034 and UM1 CA182876).

Citation Format: Hung N. Luu, Renwei Wang, Jaideep Behari, Jennifer Adams-Haduch, Andrew O. Odegaard, George Goh Bee, Aizhen Jin, Woon-Puay Koh, Jian-Min Yuan. Composite score of healthy lifestyle factors and risk of hepatocellular carcinoma: Findings from a prospective cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2344.

Association between Dietary Tomato Intake and the Risk of Hepatocellular Carcinoma: The Singapore Chinese Health Study

BACKGROUND

Intake of tomato and/or lycopene has been associated with reduced risk of several cancers, but there is no report on the association with risk of hepatocellular carcinoma (HCC).

METHODS

The associations of tomato and lycopene consumption with risk of HCC were examined in the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese ages 45 to 74 years at enrollment. Diet was assessed using a validated semiquantitative food frequency questionnaire. Cox proportional hazard regression models were used to estimate HR and its 95% confidence interval (CI) of HCC with the consumption of tomato and lycopene among all cohort participants, and unconditional logistic regression was used to assess the association by hepatitis B surface antigen (HBsAg) positivity in a nested case-control study.

RESULTS

After a mean follow-up of 17.6 years, 561 incident HCC cases were identified. Higher tomato intake was associated with lower risk of HCC after adjustment for potential confounders (P _trend < 0.001). Compared with the lowest quartile, HRs (95% CIs) of HCC for the second, third, and fourth quartile of tomato intake were 0.70 (0.56-0.88), 0.73 (0.58-0.92), and 0.63 (0.49-0.81). Among HBsAg-negative individuals, the inverse association remained (P _trend = 0.03). There was no association between lycopene intake and HCC risk (P _trend = 0.54).

CONCLUSIONS

Tomato intake may offer protection against the development of HCC, particularly among individuals without chronic infection with hepatitis B virus.

IMPACT

Tomato intake is a low-cost preventative measure against HCC that may help reduce risk due to increasing rates of nonalcoholic fatty liver disease.

Prediagnostic blood levels of organochlorines and risk of non-Hodgkin lymphoma in three prospective cohorts in China and Singapore

Specific organochlorines (OCs) have been associated with non-Hodgkin lymphoma (NHL) with varying degrees of evidence. These associations have not been evaluated in Asia, where the high exposure and historical environmental contamination of certain OC pesticides (e.g., dichlorodiphenyltrichloroethane [DDT], hexachlorocyclohexane [HCH]) are different from Western populations. We evaluated NHL risk and prediagnostic blood levels of OC pesticides/metabolites and polychlorinated biphenyl congeners in a case-control study of 167 NHL cases and 167 controls nested within three prospective cohorts in Shanghai and Singapore. Conditional logistic regression was used to analyze lipid-adjusted OC levels and NHL risk. Median levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), the primary DDT metabolite, and β-HCH were up to 12 and 65 times higher, respectively, in samples from the Asian cohorts compared to several cohorts in the United States and Norway. An increased risk of NHL was observed among those with higher β-HCH levels both overall (3rd vs. 1st tertile OR = 1.8, 95%CI = 1.0-3.2; ptrend = 0.049) and after excluding cases diagnosed within 2 years of blood collection (3rd vs. 1st tertile OR = 2.0, 95%CI = 1.1-3.9; ptrend = 0.03), and the association was highly consistent across the three cohorts. No significant associations were observed for other OCs, including p,p'-DDE. Our findings provide support for an association between β-HCH blood levels and NHL risk. This is a concern because substantial quantities of persistent, toxic residues of HCH are present in the environment worldwide. Although there is some evidence that DDT is associated with NHL, our findings for p,p'-DDE do not support an association.

Urinary Cotinine Is as Good a Biomarker as Serum Cotinine for Cigarette Smoking Exposure and Lung Cancer Risk Prediction

BACKGROUND

Cotinine is a metabolite of nicotine. Serum and urinary cotinine are validated biomarkers for cigarette exposure. Their performance for lung cancer risk prediction has not been simultaneously examined in epidemiologic studies.

METHODS

A nested case-control study, including 452 incident lung cancer cases and 452 smoking-matched controls in the Shanghai cohort study, was conducted. Mass spectrometry-based methods were used to quantify cotinine in serum and urine samples collected from current smokers at baseline, on average 10 years before cancer diagnosis of cases. Logistic regression was used to estimate ORs, 95% confidence intervals (CI), and AUC ROC for lung cancer associated with higher levels of cotinine.

RESULTS

Serum and urinary cotinine levels were significantly higher in lung cancer cases than controls. Compared with the lowest quartile serum cotinine (≤0.40 nmol/mL), the OR of lung cancer for smokers in the highest quartiles (>1.39 nmol/mL) was 5.46 (95% CI, 3.38-8.81). Similarly, the OR was 5.49 (95% CI, 3.39-8.87) for highest (>16.38 nmol/mg creatinine) relative to the lowest quartile of urinary total cotinine (≤4.11 nmol/mg creatinine). A risk prediction model yielded an AUC of 0.72 (95% CI, 0.69-0.75) for serum cotinine and 0.72 (95% CI, 0.69-0.75) for urinary total cotinine combined with smoking history.

CONCLUSIONS

Urinary and serum cotinine have the same performance in prediction of lung cancer risk for current smokers.

IMPACT

Urinary cotinine is a noninvasive biomarker that can replace serum cotinine in risk prediction of future lung cancer risk for current smokers.

Association between leukocyte telomere length and the risk of pancreatic cancer: Findings from a prospective study

INTRODUCTION

Telomeres and telomerase play important role in maintaining chromosome integrity and genomic stability. Recent epidemiologic data showed inconsistent findings which suggested that both short and long leukocyte telomeres could be associated with increased risk of pancreatic cancer. We prospectively examined the association between telomere length and pancreatic cancer risk in a population-based cohort study.

METHODS

The Singapore Chinese Health Study recruited 63,257 Chinese aged 45 to 74 years from 1993 to 1998 in Singapore. Relative telomere length in peripheral blood leukocytes was quantified using a validated monochrome multiplex quantitative polymerase chain reaction method in 26,540 participants, including 116 participants who later developed pancreatic cancer after an average of 13 years of follow-up. Cox proportional hazard regression method was used to calculate hazard ratio (HR) and its 95% confidence interval (CI) of pancreatic cancer risk associated with telomere length, with adjustment for confounding factors.

RESULTS

Longer telomeres were significantly associated with higher risk of pancreatic cancer (Ptrend = 0.02). Compared with lowest quartile, subjects with highest quartile of telomere length had an HR of 2.18 (95% CI: 1.25-3.80) for developing pancreatic cancer. In stratified analysis, this association remained among pancreatic adenocarcinoma patients but not among pancreatic non-adenocarcinoma patients. In continuous scale, the HRs and 95% CIs were 3.08 (1.17-8.11) for adenocarcinoma patients and 1.47 (0.43-5.06) for non-adenocarcinoma patients. The HRs and 95% CIs of the highest quartile of telomere length, compared with the lowest quartile, for adenocarcinoma and non-adenocarcinoma were 2.50 (1.22-5.13) and 1.63 (0.66-4.03), respectively. The length of follow-up from the collection of blood for the measurement of telomere length to the diagnosis of cancer (median = 8.0, range: from 5.0 months to 16.2 years) had no significant impact on the association between telomere length and pancreatic cancer risk.

CONCLUSIONS

The present study demonstrates that longer telomeres are associated with increased risk of overall pancreatic cancer.

Prediagnostic levels of urinary 8-epi-prostaglandin F2α and prostaglandin E2 metabolite, biomarkers of oxidative damage and inflammation, and risk of hepatocellular carcinoma

Chronic inflammation and oxidative stress play pivotal roles in the pathogenesis of hepatocellular carcinoma (HCC). We conducted a nested case-control study of 347 HCC cases and 691 matched controls within a prospective cohort of 18 244 Chinese men in Shanghai, China. The concentrations of 8-epi-prostaglandin F2α (8-epi-PGF2α), a biomarker of oxidative stress, and prostaglandin E2 (PGE2) metabolite (PGE-M), a biomarker of the inflammation mediator PGE2, were determined in baseline urine samples using validated mass spectrometry assays. 8-epi-PGF2α levels were significantly higher in HCC cases than control subjects (geometric means 0.92 versus 0.80 pmol/mg creatinine, P < 0.001). The relative risks of developing HCC for the highest relative to the lowest quartile of 8-epi-PGF2α were 2.55 (95% confidence interval = 1.62-4.01, Ptrend < 0.001). This positive 8-epi-PGF2α-HCC risk association was independent of smoking status, alcohol consumption and hepatitis B or liver cirrhosis and was present 10 years before the clinical manifestation of HCC. This study did not find any significant association between urinary PEG-M and HCC risk. This study provides direct evidence in support of the critical role of oxidative stress in the development of HCC regardless of its underlying causes.

Abstract 5043: Pre-diagnostic blood levels of organochlorines and risk of non-Hodgkin lymphoma in three population-based cohorts in China and Singapore

Background: Organochlorines (OCs) are environmentally persistent compounds that have been extensively used as pesticides and for other industrial applications. Residues of OCs have been detected at hazardous waste sites and in various environmental media worldwide and serum levels of OCs continue to be detectable in the general population. Specific OCs have been associated with non-Hodgkin lymphoma (NHL) risk with varying degrees of evidence. These associations have not been evaluated in Asia, where the exposure patterns of substantially high levels of certain OC pesticides and lower levels of polychlorinated biphenyls (PCBs) are different from Western populations. China accounted for nearly 20% of the worldwide production of dichlorodiphenyltrichloroethane (DDT) through 1983 when it was restricted, and historical usage of hexachlorocyclohexane (HCH) in China has been among the highest in the world.

Methods: We evaluated the risk of NHL in relation to pre-diagnostic blood levels of five OC pesticides/metabolites (hexachlorobenzene, β-HCH, oxychlordane, trans-nonachlor, and p,p’-DDE, the primary metabolite of DDT) and four PCB congeners (118, 138-158, 153, 180) in a case-control study of 167 NHL cases and 167 controls matched on age, sex, and blood collection date. The study was nested within three population-based cohorts of Chinese men and women in Shanghai and Singapore. Associations between lipid-adjusted OC concentrations and NHL risk were analyzed using conditional logistic regression.

Results: Median levels of p,p’-DDE and β-HCH were up to 12 and 65 times higher, respectively, in Shanghai (blood collected between 1986-2000) compared to reported levels in population-based cohorts in the United States (CLUE; Nurse’s Health Study) and Norway (Janus) with blood collected between 1972-1990. Median levels of p,p’-DDE and β-HCH were more comparable in Singapore (blood collected between 2000-2004) relative to the Western cohorts (1-2 fold concentration differences). Levels of β-HCH were associated with increased risk of overall NHL (3rd vs. 1st tertile OR=1.78, 95%CI=0.98-3.23; ptrend =0.049) in the pooled analysis of three cohorts. No significant associations were observed for other OCs and NHL risk, including for p,p’-DDE. Results for β-HCH and p,p’-DDE were consistent across cohorts.

Discussion: Associations between β-HCH and NHL risk have not been consistent in studies of Western populations. Our findings provide the first evidence suggesting associations between blood levels of β-HCH and NHL risk in a population in Asia that experienced far higher exposures. Although there is limited evidence that DDT (IARC Group 2A) is associated with NHL based on studies in Western populations, our findings among Asians, who had higher p,p’-DDE levels than reported in the general population in the West, do not support an association with environmental exposure.

Citation Format: Bryan A. Bassig, Xiao-Ou Shu, Andreas Sjodin, Woon-Puay Koh, Yu-Tang Gao, Jennifer Adams-Haduch, Mark Davis, Renwei Wang, Yong-Bing Xiang, Mark Purdue, Bu-Tian Ji, Gong Yang, Richard Jones, H. Dean Hosgood, Wei Jie Seow, Wei Hu, Wei Zheng, Jian-Min Yuan, Qing Lan, Nathaniel Rothman. Pre-diagnostic blood levels of organochlorines and risk of non-Hodgkin lymphoma in three population-based cohorts in China and Singapore [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5043.

Abstract 2681: Prediagnostic levels of urinary 8-epi-prostaglandin F2α and prostaglandin E2 metabolite, biomarkers of oxidative damage and inflammation, and risk of hepatocellular carcinoma

Background: Chronic inflammation causes persistent liver injury and consecutive regeneration, potentially leading to fibrosis and cirrhosis, and consequently, to the development of hepatocellular carcinoma (HCC). Prostaglandin E2 (PGE2) is one of the major end-products of the cyclooxygenase-2 (COX-2) pathway, an enzyme that is an important mediator of inflammation. Oxidative stress, which results from the generation of reactive oxygen species (ROS) by environmental risk factors or cellular mitochondrial dysfunction, may be involved in the progression of chronic liver disease to the development of HCC. 8-epi-prostaglandin F2α (8-epi-PGF2α) is a product of lipid peroxidation, which has been recognized as a specific, chemically stable, quantitative marker of systemic and integrated measure of oxidative stress.

Method: We evaluated the associations for urinary levels of 8-epi-PGF2α and PGE-M, a metabolite of PGE2, with HCC risk in a prospective cohort of 18,244 men in Shanghai, China. After 25 years of follow-up, 347 participants developed HCC. For each case, two control subjects were chosen and matched on age (±2 years), date of sample collection (±1 months), and neighborhood of residence. Urinary 8-epi-PGF2α and PGE-M were quantified using validated liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) assays. The logistic regression method was used to calculate the odds ratio (OR) and its 95% confidence interval (CI) associated with higher levels of both urinary 8-epi-PGF2α and PGE-M.

Results: 8-epi-PGF2α levels were significantly higher in HCC cases than control subjects (geometric means 0.92 vs 0.80 pmol/mg creatinine, P &lt;0.001). The OR of HCC for the highest relative to the lowest quartile of 8-epi-PGF2α were 2.51 (95% CI 1.60 - 3.93, P trend &lt; 0.001) after adjustment for age, cigarette smoking, alcohol consumption, liver cirrhosis, and hepatitis

1 B surface antigen. This association remained significant after excluding all HCC cases diagnosed within the first 10 years of follow-up. The present study did not find any significant association between urinary PEG-M and HCC risk.

Discussion: 8-Isoprostanes have been found to be significantly elevated in patients with non-alcoholic steatohepatitis (NASH). Our findings support a significant role of oxidative stress in the development of HCC, especially in those without traditional risk factors. The null finding on PGE-M and HCC risk is consistent with results of epidemiological studies that did not show a statistically significant association for HCC risk with use of COX-2 inhibitors.

Citation Format: Jian-Min Yuan, Menno Grouls, Steven G. Carmella, Renwei Wang, Alicia Heskin, Yang Jiang, Yuting Tan, Jennifer Adams-Haduch, Yu-Tang Gao, Stephen S. Hecht. Prediagnostic levels of urinary 8-epi-prostaglandin F2α and prostaglandin E2 metabolite, biomarkers of oxidative damage and inflammation, and risk of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2681.

Loci for human leukocyte telomere length in the Singaporean Chinese population and trans-ethnic genetic studies

Genetic factors underlying leukocyte telomere length (LTL) may provide insights into telomere homeostasis, with direct links to disease susceptibility. Genetic evaluation of 23,096 Singaporean Chinese samples identifies 10 genome-wide loci (P < 5 × 10-8). Several of these contain candidate genes (TINF2, PARP1, TERF1, ATM and POT1) with potential roles in telomere biology and DNA repair mechanisms. Meta-analyses with additional 37,505 European individuals reveals six more genome-wide loci, including associations at MPHOSPH6, NKX2-3 and TYMS. We demonstrate that longer LTL associates with protection against respiratory disease mortality [HR = 0.854(0.804-0.906), P = 1.88 × 10-7] in the Singaporean Chinese samples. We further show that the LTL reducing SNP rs7253490 associates with respiratory infections (P = 7.44 × 10-4) although this effect may not be strongly mediated through LTL. Our data expands on the genetic basis of LTL and may indicate on a potential role of LTL in immune competence.

Nicotine-N'-Oxidation by Flavin Monooxygenase Enzymes

BACKGROUND

The major mode of metabolism of nicotine is by hydroxylation via cytochrome P450 (CYP) 2A6, but it can also undergo glucuronidation by UDP-glucuronosyltransferases and oxidation by flavin monooxygenases (FMO). The goal of this study was to examine the potential importance of FMOs in nicotine metabolism and assess the potential impact of missense polymorphisms in active FMOs on nicotine-N'-oxide (NOX) formation.

METHODS

Urine samples from 106 current Chinese smokers were analyzed for nicotine metabolites by mass spectrometry. Wild-type FMOs 1-5 and their most prevalent nonsynonymous variants were cloned and overexpressed in HEK293 cells, and were tested in oxidation reactions against nicotine.

RESULTS

A strong inverse correlation was observed between the ratio of urinary 3'-hydroxycotinine/cotinine, a measure of CYP2A6 activity, and the urinary levels of NOX alone (r = -0.383; P < 0.001) or NOX measured as a ratio of total nicotine metabolites (r = -0.414; P < 0.001) in smokers. In addition to FMO1 and FMO3, the functional FMO2^427Q isoform was active against nicotine, whereas FMO4 and FMO5 exhibited low activity against nicotine (K _m > 5.0 mmol/L). Significant (P < 0.05) decreases in N'-oxidation activity (V _max/K _m) were observed for the FMO1^I303V, FMO3^N61S, FMO3^D132H, FMO3^V257M, and FMO3^E308G variants in vitro when compared with their respective wild-type isoforms; the truncated FMO2^Q472stop isoform exhibited no enzyme activity.

CONCLUSIONS

These data indicate that increases in nicotine-N'-oxidation occur in subjects with deficient CYP2A6 activity, and that several FMO enzymes are active in nicotine-N'-oxidation.

IMPACT

Several common missense FMO variants are associated with altered enzyme activity against nicotine and may play an important role in nicotine metabolism in low-CYP2A6 activity subjects.

Serologic markers of viral infection and risk of non-Hodgkin lymphoma: A pooled study of three prospective cohorts in China and Singapore

Incidence rates of non-Hodgkin lymphoma (NHL) and distributions of certain viruses differ between East Asian and Western populations. There are limited data on associations between serologic markers of multiple viral infections in pre-diagnostic blood and NHL risk in East Asians. We conducted a nested case-control study of 214 NHL cases and 214 matched controls from three population-based prospective cohorts in Shanghai and Singapore. Antibodies against antigens from herpesviruses, Hepatitis B (HBV) and C (HCV) virus and polyomaviruses were measured in plasma or serum using fluorescent bead-based multiplex assays. Conditional logistic regression was used to evaluate associations between antibody levels and NHL risk. An increased risk of NHL was observed for higher compared to lower EA-D (Odds Ratio (OR) = 2.04, 95% Confidence Interval (CI) = 1.10-3.81; ptrend  = 0.005) and ZEBRA (OR = 2.17, 95% CI = 0.96-4.89; ptrend  = 0.008) Epstein-Barr Virus (EBV) antibodies, as well as for antibody seropositivity against the IE1A human herpesvirus-6 (HHV-6) antigen (OR = 1.85, 95% CI = 1.04-3.29). An increased NHL risk was also observed for higher compared to lower antibodies against the HBV-HBc and HBe antigens. An increased risk of NHL in relation to EBV and HBV infection in East Asians is consistent with findings in several studies of Western populations, suggesting similar viral risk factors for NHL in these diverse populations with distinct patterns of NHL. The association between HHV-6 antibodies and NHL has not previously been reported in a prospective study in this population and will require replication.

Relationship of the oxidative damage biomarker 8-epi-prostaglandin F2α to risk of lung cancer development in the Shanghai Cohort Study

It has been hypothesized that the pathogenesis of lung cancer induced by cigarette smoking involves oxidative damage by free radicals. Epidemiological data on biomarkers of oxidative damage and risk of lung cancer development are sparse. A nested case-control study of 610 lung cancer cases and 610 matched controls was conducted within a prospective cohort of 18 244 Chinese men in Shanghai, China. The concentrations of 8-epi-prostaglandin F2α (8-epiPGF2α), a biomarker of oxidative stress, were determined in baseline urine samples using a validated mass-spectrometry assay. Current smokers had significantly higher level of 8-epiPGF2α than former smokers or never smokers (P < 0.001). 8-epiPGF2α levels were significantly higher in lung cancer cases than their smoking-matched controls in former and current smokers, but not different in never smokers (P for interaction = 0.019). The relative risks of developing lung cancer for former and current smokers in the highest relative to the lowest quartile of 8-epiPGF2α were 5.25 (Ptrend = 0.035) and 1.99 (Ptrend =0.007), respectively. The effect of 8-epiPGF2α and biomarkers of cigarette smoke exposure on lung cancer risk was additive; the relative risk was 5.33 (95% confidence interval = 2.65-7.51) for current smokers with the highest thirds of 8-epiPGF2α and total cotinine compared with their lowest thirds. Smokers with a heightened state of oxidative stress in response to the insults of cigarette smoking may be more susceptible to smoking-induced lung carcinogenesis.

Leukocyte telomere length in relation to risk of lung adenocarcinoma incidence: Findings from the Singapore Chinese Health Study

Telomeres are crucial in the maintenance of chromosome integrity and genomic stability. Critically short telomeres can trigger programed cell death while cells with longer telomeres may have increased likelihood of replicative errors, resulting in genetic mutations and chromosomal alterations, and ultimately promoting oncogenesis. Data on telomere length and lung cancer risk from large prospective cohort studies are spare. Relative telomere length in peripheral blood leukocytes was quantified using a validated monochrome multiplex quantitative polymerase chain reaction (qPCR) method in 26,540 participants of the Singapore Chinese Health Study. After a follow-up of 12 years, 654 participants developed lung cancer including 288 adenocarcinoma, 113 squamous cell carcinoma and 253 other/unknown histological type. The Cox proportional hazard regression was used to estimate hazard ratio (HR) and 95% confidence interval (CI). HR of lung adenocarcinoma for individuals in the highest comparing the lowest 20 percentile of telomere length was 2.84 (95% CI 1.94-4.14, p_trend  < 0.0001). This positive association was present in never smokers (p_trend  < 0.0001), ever smokers (p_trend  = 0.0010), men (p_trend  = 0.0003), women (p_trend  < 0.0001), and in shorter (p_trend  = 0.0002) and longer (p_trend  = 0.0001) duration of follow-up. There was no association between telomere length and risk of squamous cell carcinoma or other histological type of lung cancer in all or subgroups of individuals. The agreement of results from this prospective cohort study with those of previous prospective studies and Mendelian randomization studies suggest a possible etiological role of telomere length in the development of lung adenocarcinoma.

Abstract 4245: Serologic markers of infection and risk of non-Hodgkin lymphoma in a pooled prospective study of three Chinese cohorts

Background: Infections with some viruses, including HIV and Epstein-Barr Virus (EBV) in immunocompromised individuals, are known risk factors for specific subtypes of non-Hodgkin lymphoma (NHL). Epidemiological studies have also provided evidence that hepatitis viruses, and EBV in immunocompetent individuals, may also be associated with NHL. There are limited population-based prospective studies with pre-diagnostic blood samples that have comprehensively evaluated viral biomarkers and NHL risk in East Asians, in whom the descriptive characteristics of NHL and the prevalence of certain viral infections differ compared to Western populations.

Methods: We conducted a nested case-control study of 214 NHL cases and 214 controls from three population-based prospective cohorts in Shanghai and Singapore. Cases and controls were individually matched by age, sex, date of blood draw, and cohort. Antibodies to 21 antigens associated with the evaluated viruses (herpesviruses, Hepatitis B (HBV) and C (HCV), and polyomaviruses) were measured in plasma/serum using fluorescent bead-based multiplex serology. Conditional logistic regression was used to evaluate associations between viral antibody levels measured as median fluorescence intensity and NHL.

Results: For herpesviruses, an increased risk of NHL was observed for higher compared to lower early antigen diffuse (EA-D) (OR = 2.2, 95% CI = 1.2-4.1) and BZLF1-encoded replication activator (ZEBRA) (OR = 2.2, 95% CI = 1.0-4.9) antibodies (rsp = +0.5) associated with EBV. An increased risk of NHL was also observed among those seropositive for the intermediate-early 1A antigen (OR = 1.9, 95% CI = 1.0-3.3; rsp with EBV antibodies = +0.2) associated with human herpesvirus-6 (HHV-6). For hepatitis viruses, a significant NHL risk was observed for higher compared to lower antibodies to the HBV-associated core (HBc) antigen (OR = 1.8, 95% CI = 1.1-3.1), and this risk was particularly apparent in those with the highest HBc and EBV EA-D antibody levels (OR = 4.2, 95% CI = 1.4-12.7) compared to the lowest. Seropositivity to HCV was low (1.4% cases; 0.9% controls). No associations with NHL risk were observed for individual polyomaviruses (BK, JC, TSV, MCV). Discussion: Our study of serologic markers of infection and NHL risk in three prospective population-based studies of Chinese individuals suggests a role of specific viral agents in lymphomagenesis. The findings for EBV are consistent with some data from Western cohorts and indicate that EBV reactivation may be associated with NHL risk in the Chinese general population. HHV-6 is a lymphotropic virus that has been observed in some retrospective studies to be associated with lymphoma, but to our knowledge has not previously been associated with NHL prospectively in the general population. HBV is endemic to regions of East Asia, including China, and our data suggest that high levels of antibodies to the HBc antigen may be a marker for NHL risk.

Citation Format: Bryan A. Bassig, Angelika Michel, Xiao-Ou Shu, Woon-Puay Koh, Yu-Tang Gao, Lesley M. Butler, Mark Purdue, Yong-Bing Xiang, Jennifer Adams-Haduch, Renwei Wang, Nicole Brenner, Tim Waterboer, Martina Willhauck-Fleckenstein, Bu-Tian Ji, H. Dean Hosgood, Charles S. Rabkin, Jason Y.Y. Wong, Jinming Zhang, Wei Hu, Gong Yang, Wong-Ho Chow, Michael Pawlita, Wei Zheng, Jian-Min Yuan, Qing Lan, Nathaniel Rothman. Serologic markers of infection and risk of non-Hodgkin lymphoma in a pooled prospective study of three Chinese cohorts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4245. doi:10.1158/1538-7445.AM2017-4245

CYP2A6 genetic polymorphisms and biomarkers of tobacco smoke constituents in relation to risk of lung cancer in the Singapore Chinese Health Study

Cytochrome P450 2A6 (CYP2A6) catalyzes the metabolism of nicotine and the tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Genetic variation in CYP2A6 may affect smoking behavior and contribute to lung cancer risk. A nested case-control study of 197 lung cancer cases and 197 matched controls was conducted within a prospective cohort of 63 257 Chinese men and women in Singapore. Quantified were five genetic variants of CYP2A6 (*1A, *4, *7, *9 and *12) and urinary metabolites of nicotine [total nicotine, total cotinine, total trans-3'-hydroxycotinine (3HC)] and NNK (total NNAL, free NNAL, NNAL-glucuronide, NNAL-N-glucuronide, and NNAL-O-glucuronide). Higher urinary metabolites of nicotine and NNK were significantly associated with a 2- to 3-fold increased risk of lung cancer after adjustment for smoking intensity and duration. Lower CYP2A6-determined nicotine metabolizer status was significantly associated with a lower ratio of total 3HC over total cotinine, lower total nicotine equivalent and reduced risk of developing lung cancer (all Ptrend < 0.001). Compared with normal metabolizers, odds ratios (95% confidence intervals) of developing lung cancer for intermediate, slow and poor metabolizers determined by CYP2A6 genotypes were 0.85 (0.41-1.77), 0.55 (0.28-1.08) and 0.32 (0.15-0.70), respectively, after adjustment for smoking intensity and duration and urinary total nicotine equivalents. Thus the reduced risk of lung cancer in smokers with lower CYP2A6 activity may be explained by lower consumption of cigarettes, less intense smoking and reduced CYP2A6-catalyzed activation of the tobacco-specific lung carcinogen NNK.

Abstract 2622: A LC-MS/MS method to quantify specific dietary isothiocyanates in human urine for epidemiological studies

Epidemiological studies have demonstrated an inverse relationship between the intake of cruciferous vegetables and risk of cancers. The protective effects may be attributed to glucosinolates and glucobrassicins in these vegetables. While glucosinolates and glucobrassicins are not chemopreventive, their metabolites, isothiocyanates (ITCs), indole-3-carbinol (I3C), and 3,3′-diindolylmethane (DIM), have been shown to inhibit tumorigenesis in rodent models. In the past studies the total ITCs intake was estimated through food frequency questionnaires and/or urinary total ITC by a HPLC-based method. Self-reported intake of cruciferous vegetables has inherent limitations in estimating the intake of ITCs because of differences in the contents of their precursors present in different kinds of cruciferous vegetables, different locations and methods of cultivation, or different methods of food preparation. Animal and cell culture studies have shown that different types of ITCs have different anticancer properties and potency, suggesting that they are not equal in protecting against the development of cancers. The lack of a reliable method to quantify specific ITCs derived from dietary intake of cruciferous vegetables hinders the investigation of the role of specific ITCs against the development of cancer in human populations. To address this deficiency, we developed a flexible, highly sensitive, fast and reliable quantitative liquid chromatography mass spectrometry method (LC-MS/MS) for detecting and quantifying common dietary ITCs plus DIM in human urine. Urinary ITCs are measured as mercapturic acid conjugates (ITCs-NAC), predominant metabolite of ITCs, using multiple reaction monitoring (MRM) technique and deuterated [2H3]-ITCs-NAC as internal standards. DIM is quantified in separate experiment using [2H2]-DIM internal standard. The method was validated by a small set of previously analyzed samples from Singapore Chinese Health Study. We found an excellent correlation between previously reported total ITCs levels and sum of ITCs detected by newly developed method. The combination of minimal sample preparation, ultra-performance liquid chromatography, and highly sensitive mass spectrometer resulted in a method that is fast (below 10 min for ITCs and 12 min for DIM) and sensitive (low femtomolar LOQ) amenable to population studies.

Citation Format: Marcin Dyba, Jian-Min Yuan, Jennifer Adams-Haduch, Fung-Lung Chung. A LC-MS/MS method to quantify specific dietary isothiocyanates in human urine for epidemiological studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2622.

Abstract 4281: Mitochondrial DNA copy number, urinary isoprostanes and colorectal cancer risk

Previous epidemiological studies on mitochondrial DNA (mtDNA) copy number and risk of colorectal cancer have yielded mixed results. One study reported a positive association, another reported an inverse association, and a third, a U-shaped association of mtDNA copy number with colorectal cancer risk. Since oxidative stress is one of the proposed underlying mechanisms that may link mtDNA copy number variation to colorectal cancer risk, we conducted a matched case-control study of incident colorectal cancer nested within the Singapore Chinese Health Study. Pre-diagnostic blood and urine samples were obtained from 448 colorectal cancer cases and 869 age- and sex-matched controls. The mtDNA copy number in peripheral white cells was measured using real time PCR and urinary F2-isoprostanes were quantified using a liquid chromatography mass spectrometry based method. Conditional logistic regression was used to estimate associations of mtDNA copy number and urinary F2-isoprostanes with incident colorectal cancer. The odds ratios (OR) and 95% confidence intervals (95% CI) for those in the highest relative to those in the lowest quartiles of relative mtDNA copy numbers and urinary F2-isoprostanes were 1.02 (95% CI 0.72 - 1.43; p for trend = 0.56) and 1.11 (95% CI 0.78-1.59; p for trend = 0.35) respectively. Urinary F2-isoprostanes levels were not associated with the mtDNA copy number among the controls (r = 0.03; p = 0.33). The results of this prospective study suggest that white blood cell mtDNA copy number or urinary levels of F2-isoprostanes in biospecimens collected several years prior to the diagnosis of colorectal cancer may not be associated with risk of developing colorectal cancer.

Citation Format: Bharat Thyagarajan, Renwei Wang, Woon-Puay Koh, Helene Barcelo, Jennifer Adams-Haduch, Weihua Guan, Roberd M. Bostick, Jian-Min Yuan, Myron D. Gross. Mitochondrial DNA copy number, urinary isoprostanes and colorectal cancer risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4281.

Genetic determinants of cytochrome P450 2A6 activity and biomarkers of tobacco smoke exposure in relation to risk of lung cancer development in the Shanghai cohort study

Cytochrome P450 2A6 (CYP2A6) catalyzes nicotine metabolism and contributes to the metabolism of the tobacco-specific lung carcinogen, NNK. Genetic variation in CYP2A6 may affect smoking behavior and contribute to lung cancer risk. A nested case-control study of 325 lung cancer cases and 356 controls was conducted within a prospective cohort of 18,244 Chinese men in Shanghai, China. Quantified were 4 allelic variants of CYP2A6 [*1(+51A), *4, *7, and *9] and urinary total nicotine, total cotinine, total trans-3'-hydroxycotinine (3HC) and total NNAL (an NNK metabolite). Calculated were total nicotine equivalents (TNE), the sum of total nicotine, total cotinine and total 3HC and the total 3HC:total cotinine ratio as a measure of CYP2A6 activity. The nicotine metabolizer status (normal, intermediate, slow and poor) was determined by CYP2A6 genotypes. The smoking-adjusted odds ratios (95% confidence intervals) of lung cancer for the highest vs lowest quartile of total nicotine, total cotinine, total 3HC, TNE and total NNAL were 3.03 (1.80-5.10), 4.70 (2.61-8.46), 4.26 (2.37-7.68), 4.71 (2.61-8.52), and 3.15 (1.86-5.33) (all Ptrend  < 0.001), respectively. Among controls CYP2A6 poor metabolizers had a 78% lower total 3HC:total cotinine ratio and 72% higher total nicotine (Ptrend ≤ 0.002). Poor metabolizers had an odds ratio of 0.64 (95% confidence interval = 0.43-0.97) for lung cancer, which was statistically nonsignificant (odds ratio = 0.74, 95% confidence interval = 0.48-1.15) after adjustment for urinary TNE and smoking intensity and duration. The lower lung cancer risk observed in CYP2A6 poor metabolizers is partially explained by the strong influence of CYP2A6 genetic polymorphisms on nicotine uptake and metabolism.

Clinical Trial of 2-Phenethyl Isothiocyanate as an Inhibitor of Metabolic Activation of a Tobacco-Specific Lung Carcinogen in Cigarette Smokers

2-Phenethyl isothiocyanate (PEITC), a natural product found as a conjugate in watercress and other cruciferous vegetables, is an inhibitor of the metabolic activation and lung carcinogenicity of the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in F344 rats and A/J mice. We carried out a clinical trial to determine whether PEITC also inhibits the metabolic activation of NNK in smokers. Cigarette smokers were recruited and asked to smoke cigarettes containing deuterium-labeled [pyridine-D4]NNK for an acclimation period of at least 1 week. Then subjects were randomly assigned to one of two arms: PEITC followed by placebo, or placebo followed by PEITC. During the 1-week treatment period, each subject took PEITC (10 mg in 1 mL of olive oil, 4 times per day). There was a 1-week washout period between the PEITC and placebo periods. The NNK metabolic activation ratio [pyridine-D4]hydroxy acid/total [pyridine-D4]NNAL was measured in urine samples to test the hypothesis that PEITC treatment modified NNK metabolism. Eighty-two smokers completed the study and were included in the analysis. Overall, the NNK metabolic activation ratio was reduced by 7.7% with PEITC treatment (P = 0.023). The results of this trial, while modest in effect size, provide a basis for further investigation of PEITC as an inhibitor of lung carcinogenesis by NNK in smokers. Cancer Prev Res; 9(5); 396-405. ©2016 AACR.

Abstract 846: Soluble levels of CD27 and CD30 are associated with risk of non-Hodgkin lymphoma in a pooled analysis of three prospective cohorts of Chinese men and women in Shanghai and Singapore

Recent prospective studies conducted in Western populations among mostly Caucasians have suggested that higher levels of soluble CD27 (sCD27) and soluble CD30 (sCD30), two markers indicative of B-cell activation, are associated with risk of non-Hodgkin lymphoma (NHL), with significant associations persisting in individuals who were diagnosed with NHL &gt;10 years after blood collection. However, there are currently no molecular epidemiologic data evaluating whether these biomarkers are associated with NHL risk in East Asian populations, in whom the descriptive characteristics of NHL in terms of subtype distributions and incidence rates are quite different from those in Western countries. To explore potential mechanistic commonalities for NHL in these populations, we conducted a pooled nested case-control study from three prospective studies of Chinese men and women including 218 NHL cases and 218 individually matched controls. Levels of sCD27 and sCD30 were measured in all study subjects at the same time using ELISA. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) according to quartile levels of sCD27 or sCD30 in all study controls. An increased risk of NHL in the pooled population was observed for elevated levels of both sCD27 and sCD30. Compared to the lowest quartile, ORs (95% CIs) for the 2nd, 3rd, and 4th quartiles of sCD27 were 1.60 (0.83-3.09), 1.94 (0.98-3.83), and 4.45 (2.25-8.81), respectively (ptrend = 0.000005). The corresponding ORs (95% CIs) for sCD30 were 1.74 (0.85-3.58), 1.86 (0.94-3.67), and 5.15 (2.62-10.12) (ptrend = 0.0000002). These associations remained statistically significant in individuals diagnosed with NHL 10 or more years after blood draw. Notably, the magnitude of the associations with risk of NHL was very similar to those in Western populations in previous studies. These findings of the similar association between sCD27 or sCD30 and NHL risk across different populations support an important underlying mechanism of B-cell activation in lymphomagenesis.

Citation Format: Bryan A. Bassig, Xiao-Ou Shu, Woon-Puay Koh, Yu-Tang Gao, Mark P. Purdue, Lesley M. Butler, Jennifer Adams-Haduch, Yong-Bing Xiang, Troy J. Kemp, Renwei Wang, Ligia A. Pinto, Tongzhang Zheng, Bu-Tian Ji, H. Dean Hosgood, Wei Hu, Gong Yang, Heping Zhang, Wong-Ho Chow, Christopher Kim, Wei Jie Seow, Wei Zheng, Jian-Min Yuan, Qing Lan, Nathaniel Rothman. Soluble levels of CD27 and CD30 are associated with risk of non-Hodgkin lymphoma in a pooled analysis of three prospective cohorts of Chinese men and women in Shanghai and Singapore. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 846. doi:10.1158/1538-7445.AM2015-846

Soluble levels of CD27 and CD30 are associated with risk of non-Hodgkin lymphoma in three Chinese prospective cohorts

Prospective studies conducted in Western populations have suggested that alterations in soluble CD27 (sCD27) and soluble CD30 (sCD30), two markers indicative of B-cell activation, are associated with risk of non-Hodgkin lymphoma (NHL). Given that the characteristics of NHL in East Asia differ from the West and mechanistic commonalities between these populations with respect to the role of intermediate endpoint biomarkers in lymphomagenesis have not been explored, we conducted a pooled nested case-control study from three prospective studies of Chinese men and women including 218 NHL cases and 218 individually matched controls. Compared with the lowest quartile, ORs (95% CIs) for the second, third and fourth quartiles of sCD27 were 1.60 (0.83-3.09), 1.94 (0.98-3.83) and 4.45 (2.25-8.81), respectively (p(trend) = 0.000005). The corresponding ORs for sCD30 were 1.74 (0.85-3.58), 1.86 (0.94-3.67) and 5.15 (2.62-10.12; p(trend) = 0.0000002). These associations remained statistically significant in individuals diagnosed with NHL 10 or more years after blood draw. Notably, the magnitude of the associations with NHL risk was very similar to those in Western populations in previous studies. These findings of the similar association between sCD27 or sCD30 and NHL risk across different populations support an important underlying mechanism of B-cell activation in lymphomagenesis.