Biliary Tract Cancer

Ingestion of Nitrate and Nitrite and Risk of Stomach and Other Digestive System Cancers in the Iowa Women's Health Study

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC) which are potent animal carcinogens for the organs of the digestive system. We evaluated dietary intakes of nitrate and nitrite, as well as nitrate ingestion from drinking water (public drinking water supplies (PWS)), in relation to the incidence (1986-2014) of cancers of the esophagus (n = 36), stomach (n = 84), small intestine (n = 32), liver (n = 31), gallbladder (n = 66), and bile duct (n = 58) in the Iowa Women's Health Study (42,000 women aged from 50 to 75 in 1986). Dietary nitrate and nitrite were estimated using a food frequency questionnaire and a database of nitrate and nitrite levels in foods. Historical nitrate measurements from PWS were linked to the enrollment address by duration. We used Cox regression to compute hazard ratios (HR) and 95% confidence intervals (CI) for exposure quartiles (Q), tertiles (T), or medians, depending on the number of cancer cases. In adjusted models, nitrite intake from processed meats was associated with an increased risk of stomach cancer (HRQ4vsQ1 = 2.2, CI: 1.2-4.3). A high intake of total dietary nitrite was inversely associated with gallbladder cancer (HRQ4vsQ1 = 0.3, CI: 0.1-0.96), driven by an inverse association with plant sources of nitrite (HRQ4vsQ1 = 0.3, CI: 0.1-0.9). Additionally, small intestine cancer was inversely associated with a high intake of animal nitrite (HRT3vsT1 = 0.2, CI: 0.1-0.7). There were no other dietary associations. Nitrate concentrations in PWS (average, years ≥ 1/2 the maximum contaminant level) were not associated with cancer incidence. Our findings for stomach cancer are consistent with prior dietary studies, and we are the first to evaluate nitrate and nitrite ingestion for certain gastrointestinal cancers.

Smoking, Alcohol, and Biliary Tract Cancer Risk: A Pooling Project of 26 Prospective Studies

BACKGROUND

Tobacco and alcohol are well-established risk factors for numerous cancers, yet their relationship to biliary tract cancers remains unclear.

METHODS

We pooled data from 26 prospective studies to evaluate associations of cigarette smoking and alcohol consumption with biliary tract cancer risk. Study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for associations with smoking and alcohol consumption were calculated. Random-effects meta-analysis produced summary estimates. All statistical tests were two-sided.

RESULTS

Over a period of 38 369 156 person-years of follow-up, 1391 gallbladder, 758 intrahepatic bile duct, 1208 extrahepatic bile duct, and 623 ampulla of Vater cancer cases were identified. Ever, former, and current smoking were associated with increased extrahepatic bile duct and ampulla of Vater cancers risk (eg, current vs never smokers HR = 1.69, 95% CI = 1.34 to 2.13 and 2.22, 95% CI = 1.69 to 2.92, respectively), with dose-response effects for smoking pack-years, duration, and intensity (all Ptrend < .01). Current smoking and smoking intensity were also associated with intrahepatic bile duct cancer (eg, >40 cigarettes per day vs never smokers HR = 2.15, 95 % CI = 1.15 to 4.00; Ptrend = .001). No convincing association was observed between smoking and gallbladder cancer. Alcohol consumption was only associated with intrahepatic bile duct cancer, with increased risk for individuals consuming five or more vs zero drinks per day (HR = 2.35, 95%CI = 1.46 to 3.78; Ptrend = .04). There was evidence of statistical heterogeneity among several cancer sites, particularly between gallbladder cancer and the other biliary tract cancers.

CONCLUSIONS

Smoking appears to increase the risk of developing all biliary tract cancers except gallbladder cancer. Alcohol may increase the risk of intrahepatic bile duct cancer. Findings highlight etiologic heterogeneity across the biliary tract.

Associations between autoimmune conditions and hepatobiliary cancer risk among elderly US adults

Growing evidence suggests that people with autoimmune conditions may be at increased risk of hepatobiliary tumors. In the present study, we evaluated associations between autoimmune conditions and hepatobiliary cancers among adults aged ≥66 in the United States. We used Surveillance, Epidemiology, and End Results (SEER)-Medicare data (1992-2013) to conduct a population-based, case-control study. Cases (n = 32,443) had primary hepatobiliary cancer. Controls (n = 200,000) were randomly selected, cancer-free adults frequency-matched to cases by sex, age and year of selection. Using multivariable logistic regression, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations with 39 autoimmune conditions identified via Medicare claims. We also conducted separate analyses for diagnoses obtained via inpatient versus outpatient claims. Sixteen conditions were associated with at least one hepatobiliary cancer. The strongest risk estimates were for primary biliary cholangitis with hepatocellular carcinoma (OR: 31.33 [95% CI: 23.63-41.56]) and primary sclerosing cholangitis with intrahepatic cholangiocarcinoma (7.53 [5.73-10.57]), extrahepatic cholangiocarcinoma (5.59 [4.03-7.75]), gallbladder cancer (2.06 [1.27-3.33]) and ampulla of Vater cancer (6.29 [4.29-9.22]). Associations with hepatobiliary-related conditions as a group were observed across nearly all cancer sites (ORs ranging from 4.53 [95% CI: 3.30-6.21] for extrahepatic cholangiocarcinoma to 7.18 [5.94-8.67] for hepatocellular carcinoma). Restricting to autoimmune conditions diagnosed via inpatient claims, 6 conditions remained associated with at least one hepatobiliary cancer, and several risk estimates increased. In the outpatient restricted analysis, 12 conditions remained associated. Multiple autoimmune conditions are associated with hepatobiliary cancer risk in the US Medicare population, supporting a shared immuno-inflammatory etiology to these cancers.

Gallbladder cancer incidence in Gwalior district of India: Five-year trend based on the registry of a regional cancer center

BACKGROUND

We have reported here the 5-year incidence (2004-2008) of gallbladder cancer (GBC) in North Central India along with its descriptive epidemiology. This provides potential clues for better prevention. The present study has also evaluated the association of ABO blood groups with GBC.

PATIENTS AND METHODS

The study comprised 742 GBC cases referred to the regional cancer hospital, Gwalior, during 2004-2008. The demographic statistics of Gwalior district was considered to calculate the relative risk and incidence rates. ABO blood group distribution amongst 90,000 healthy subjects registered in the local blood bank during 2002-2007 was taken as controls to study the association of blood groups with GBC.

RESULTS

The age-standardized total incidence rate of GBC was calculated to be 7.16/1,00,000. The relative risk of females getting GBC was 2.693 at 95% confidence interval of 2.304-3.151 (P < 0.0001). The females formed 69.5% of total cancer cases, with age-standardized incidence rate of 10/1,00,000. The mean age of male and female GBC cases was found to be 55.4 years (SD = 13, SE = 0.77) and 51.5 years (SD = 12.3, SE = 0.50), respectively. The blood groups A (P = 0.0022) and AB (P < 0.0001) had a positive association with GBC with significant level of differences in comparison to controls.

CONCLUSION

Our study provided an estimate of a 5-year incidence of GBC in North Central India for the first time. With regard to the association of risk factors like obesity, age, and urban living with GBC, the findings of the present study are contradictory to the general opinion. Blood groups A and AB were found to be associated with GBC, which would be provisional for further investigations.

Overweight, obesity and the risk of gallbladder and extrahepatic bile duct cancers: A meta-analysis of observational studies

OBJECTIVE

Epidemiological studies have repeatedly investigated the association between excess body weight and the risk of biliary tract cancer with inconsistent results. The objective of this study was to quantitatively assess the associations between overweight and obesity and the risk of biliary tract cancer.

METHODS

A comprehensive search of PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases up to August 2015 was conducted, and the reference lists of retrieved articles for additional relevant studies were manually searched.

RESULTS

Fourteen prospective cohort studies and 15 case-control studies were included in this meta-analysis. These studies included 11,448,397 participants (6,733 patients with gallbladder cancer [GBC] and 5,798 patients with extrahepatic bile duct cancer [EBDC]) with follow-up durations ranging from 5 to 23 years. Among overweight adults, the pooled RR was 1.17 (95% CI, 1.07-1.28) for GBC and 1.26 (95% CI, 1.14-1.39) for EBDC, and among people with obesity, the pooled RR was 1.62 (95% CI, 1.49-1.75) for GBC and 1.48 (95% CI, 1.21-1.81) for EBDC. Visual inspection of the funnel plots and the Begg's and the Egger's tests did not show enough evidence of publication bias.

CONCLUSIONS

Integrated evidence from this meta-analysis suggests that excess body weight is associated with a significantly increased risk of GBC and EBDC.

Medical conditions, family history of cancer, and the risk of biliary tract cancers

BACKGROUND

Scanty data exist on the role of personal medical conditions, except for gallstones, and family history of cancer on the risk of biliary tract cancers (BTC).

METHODS

We analyzed this issue using data from two Italian case-control studies, including 159 cases of BTC and 795 matched hospital controls. Odds ratios (ORs) of BTC and corresponding 95% confidence intervals (CIs) were estimated using multiple logistic regression models.

RESULTS

Gallstones were associated with a 2-fold excess risk of BTC (95% CI 1.24-3.45). No significant associations were observed with other conditions investigated, including diabetes (OR 1.15, 95% CI 0.63-2.11), hypertension (OR 0.65, 95% CI 0.39-1.11), hyperlipidemia (OR 0.61, 95% CI 0.31-1.21), allergy (OR 0.64, 95% CI 0.29-1.40), gastroduodenal ulcer (OR 0.52, 95% CI 0.24-1.12), hepatitis (OR 2.02, 95% CI 0.35-11.67), benign thyroid diseases (OR 1.16, 95% CI 0.56-2.40), hysterectomy (OR 1.19, 95% CI 0.53-2.68), unilateral oophorectomy (OR 1.75, 95% CI 0.44-6.93), and bilateral oophorectomy (OR 2.48, 95% CI 0.79-7.82). We found an excess risk of BTC in relation to family history of any cancer (OR 1.52, 95% CI 1.03-2.24) and family history of gallbladder cancer (OR 3.83, 95% CI 0.59-24.75).

CONCLUSIONS

The present study confirms a strong association between BTC and history of gallstones, and provides further evidence of a positive association with family history of cancer.

Cholangiocarcinoma among workers in the printing industry: using the NOCCA database to elucidate the generalisability of a cluster report from Japan

OBJECTIVES

A cluster of 11 cases of cholangiocarcinoma (CC) was observed in a small Japanese printing firm. To elucidate whether the identified cluster is indicative of an elevated risk of CC among workers in the printing industry at large, we explored the risk of cancer of the liver and CC among individuals employed in the printing industry in a large cohort set-up in four Nordic countries (Finland, Iceland, Norway and Sweden) over a period of 45 years.

METHODS

The cohort was set-up by linking occupational information from censuses to national cancer registry data utilising personal identity codes in use in all Nordic countries. We calculated standardised incidence ratios (SIRs) for men and women working in the printing industry, and stratified by occupational category (typographers, printers, lithographers, bookbinders).

RESULTS

Among men, we observed elevated SIRs for cancer of the liver (1.35, 95% CI 1.14 to 1.60; 142 cases), specifically intrahepatic CC (2.34, 95% CI 1.45 to 3.57; 21 cases). SIRs for liver cancer were especially elevated among printers and lithographers, and SIRs for intrahepatic CC among typographers and printers. SIRs for extrahepatic CC were not elevated. SIRs for women followed a similar pattern but the number of cases was low.

CONCLUSIONS

Our study supports the notion that the finding of excess CC risk among workers in a small Japanese printing firm possibly extends beyond this specific firm and country. Further studies should focus on the specific exposures that occur in the printing industry.

Biliary tract cancer incidence in the United States-Demographic and temporal variations by anatomic site

We evaluated incidence patterns of biliary tract cancers (gallbladder, extrahepatic bile duct, ampulla of Vater and not otherwise specified) to provide potential insight into the etiology of these cancers. Data were obtained from the population-based Surveillance, Epidemiology and End Results program. Rates for cases diagnosed during 1992-2009 were calculated by racial/ethnic, gender and age groups. Temporal trends during 1974-2009 and annual percentage changes (APC) during 1992-2009 were estimated. Age-adjusted rates by site were higher among American Indian/Alaska Natives, Hispanics (white) and Asian/Pacific Islanders (Asian/PI) and lower among whites and blacks. Gallbladder cancer was more common among women in all ethnic groups (female-to-male incidence rate ratio [IRR] ranged from 1.24 to 2.86), but bile duct and ampulla of Vater cancers were more common among men (female-to-male IRR 0.57 to 0.82). Gallbladder cancer rates declined among all racial/ethnic and gender groups except blacks (APC -0.4% to -3.9%). In contrast, extrahepatic bile duct cancer rates rose significantly in most female racial/ethnic groups; the APCs among whites were 0.8 among females and 1.3 among males, both significant. Rates for ampulla of Vater cancer decreased among Asian/PI females (APC -2.7%) but remained stable for the other groups. In addition to confirming that biliary tract cancer incidence patterns differ by gender and site and that the gallbladder cancer incidence rates have been declining, our study provides novel evidence that extrahepatic bile duct cancer rates are rising. These observations may help guide future etiologic studies.

Inflammatory gene variants and the risk of biliary tract cancers and stones: a population-based study in China

Background

Genetic variants in inflammation-related genes have been associated with biliary stones and biliary tract cancers in previous studies.

Methods

To follow-up on these findings, we examined 35 single nucleotide polymorphism (SNPs) in 5 genes related to inflammation (IL8, NFKBIL, RNASEL, TNF, and VEGFA) in 456 participants with incident biliary tract cancer cases (262 gallbladder, 141 extrahepatic bile duct, 53 ampulla of Vater), 982 participants with biliary stones, and 860 healthy controls in a population–based case–control study in Shanghai, China.

Results

Suggestive associations were observed for SNPs in VEGFA with biliary stones, IL8 with gallbladder and ampulla of Vater cancers, and RNASEL with ampulla of Vater cancer (false discovery rate≤0.2).

Conclusion

These findings provide additional support for the role of inflammation in biliary stones and biliary tract cancer risk and need further validation.

Metabolic syndrome and insulin resistance in relation to biliary tract cancer and stone risks: a population-based study in Shanghai, China

Background:

Serum lipids, diabetes, and obesity, individual components of metabolic syndrome, are associated with biliary tract cancer and stone risk, but the associations of metabolic syndrome or insulin resistance with biliary tract cancers and stones are not well studied.

Methods:

In this population-based case-control study in Shanghai, China (627 biliary tract cancers, 1037 biliary stones, and 959 controls), metabolic syndrome was defined as the presence of any three of the five components, including high waist circumference, high triglycerides, low high-density lipoprotein cholesterol (HDL), high blood pressure, and diabetes. Insulin resistance and β-cell function were assessed, using homeostasis assessment models.

Results:

Metabolic syndrome was significantly associated with gallbladder cancer (odds ratio (OR)=2.75, 95% confidence interval (95% CI)=1.82–4.15) and biliary stones (OR=1.64, 95% CI=1.24–2.16), with a significant dose effect with increasing number of metabolic syndrome components (P trend <0.0001). The observed association persisted among subjects without a history of diabetes. The association between insulin resistance and gallbladder cancer was borderline (P trend=0.06). There was a significant inverse association between β-cell function and gallbladder cancer risk (P trend <0.001).

Conclusion:

Our findings suggest that metabolic syndrome and insulin resistance have a role in the aetiology of biliary tract cancers and biliary stones, and if confirmed, they imply that lifestyle control of these factors may lower the risk of biliary stones and biliary tract cancer.

Medical history and the risk of biliary tract cancers in Shanghai, China: implications for a role of inflammation

Several lines of evidence suggest that inflammation may play a role in the etiology of biliary tract cancers. To examine further the role of inflammation, we evaluated the associations between self-reported inflammatory-related medical conditions and the risk of biliary tract cancers in a population-based case-control study in Shanghai, China. Our analysis included 368 gallbladder cancer cases, 191 bile duct cancer cases, 68 ampulla of Vater cancer cases, and 959 healthy subjects. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for biliary tract cancers in relation to six inflammation-related conditions. Gallbladder cancer was significantly associated with cholecystitis occurring at least 5 years prior to interview (OR = 1.7, 95% CI 1.1-2.9). Even though biliary stones did not significantly modify the associations between cholecystitis and gallbladder cancer, 90% of the gallbladder cancer cases with cholecystitis also had biliary stones, indicating that stones likely play an important role in the link between cholecystitis and gallbladder cancer. Among subjects who smoked and drank alcohol, a history of gastric (OR = 4.3, 95% CI 1.2-15.0) or duodenal ulcers (OR = 3.7, 1.2-12.0) was associated with an excess risk of gallbladder cancer. Although the mechanisms are unclear, our results further support the role for inflammation in the etiology of biliary tract cancers.

Risk of primary non-breast cancer after female breast cancer by age at diagnosis

BACKGROUND

Women diagnosed with breast cancer at young age have been shown to be at higher risk of developing a new primary cancer than women diagnosed at older ages, but little is known about whether adjustment for calendar year of breast cancer diagnosis, length of follow-up, and/or breast cancer treatment alters the risk pattern by age.

METHODS

We identified 304,703 women diagnosed with breast cancer during 1943 to 2006 in the Cancer Registries of Denmark, Norway, and Finland. Relative risks (RR) of subsequent non-breast cancer by age at cancer diagnosis were calculated using Poisson regression models adjusted for country, calendar period, length of follow-up, and treatment. Excess absolute risks (EAR) were also calculated.

RESULTS

The RR for all cancer sites except breast cancer decreased with increasing age both with and without adjustments. The RR and the EAR differed for each age at diagnosis category until the women reached their late 70s. Many specific cancer forms contributed to the overall risk pattern by age with endometrial cancer as 1 exception.

CONCLUSIONS

The age at breast cancer diagnosis is an essential risk factor for being diagnosed with a new primary non-breast cancer and the level of risk for specific ages at diagnosis may hold for many years after the diagnosis. Occurrence of endometrial cancer after breast cancer seems to follow a distinct age pattern different from that seen for most other cancer types.

IMPACT

Future studies should aim at exploring the underlying explanations for the age-related findings.

Chronic typhoid infection and the risk of biliary tract cancer and stones in Shanghai, China

Previous studies have shown a positive association between chronic typhoid carriage and biliary cancers. We compared serum Salmonella enterica serovar Typhi antibody titers between biliary tract cancer cases, biliary stone cases without evidence of cancer, and healthy subjects in a large population-based case-control study in Shanghai, China.

Participants included 627 newly diagnosed primary biliary tract cancer patients; 1,037 biliary stone cases (774 gallbladder and 263 bile-duct) and 959 healthy subjects without a history of cancer, randomly selected from the Shanghai Resident Registry.

Overall only 6/2,293 (0.26%) were Typhi positive. The prevalence of Typhi was 1/457 (0.22%), 4/977 (0.41%), and 1/859 (0.12%) among cancer cases, biliary-stone cases, and population controls, respectively.

We did not find an association between Typhi and biliary cancer in Shanghai, due to the very low prevalence of chronic carriers in this population.

The low seroprevalence of S. Typhi in Shanghai is unlikely to explain the high incidence of biliary cancers in this population.

Trends in survival of patients diagnosed with cancer of the digestive organs in the Nordic countries 1964-2003 followed up to the end of 2006

Cancers of the digestive organs (including the oesophagus, stomach, small intestine, colon, rectum and anus, liver, gallbladder, and pancreas) constitute one-fifth of all cancer cases in the Nordic countries and is a group of diseases with diverse time trends and varying consequences for public health. In this study we examine trends in relative survival in relation to the corresponding incidence and mortality rates in the Nordic countries during the period 1964-2003.

MATERIAL AND METHODS

Data were retrieved from the NORDCAN database for the period 1964 to 2003, grouped into eight 5-year periods of diagnosis. The patients were followed up until the end of 2006. Analysis comprised trends in 5-year relative survival, excess mortality and age-specific relative survival.

RESULTS

Survival following cancers of the colon and rectum has increased continuously over the observed period, yet Danish patients fall behind those in the other Nordic countries. The largest inter-country variation is seen for the rare cancers in the small intestine. There has been little increase in prognosis for patients diagnosed with cancers of the liver, gallbladder or pancreas; 5-year survival is generally below 15%. Survival also remains consistently low for patients with oesophageal cancer, while minor increases in survival are seen among stomach cancer patients in all countries except Denmark. The concomitant incidence and mortality rates of stomach cancer have steadily decreased in each Nordic country at least since 1964.

CONCLUSION

While the site-specific variations in mortality and survival largely reflect the extent of changing and improving diagnostic and clinical practices, the incidence trends highlight the importance of risk factor modification. Alongside the ongoing clinical advances, effective primary prevention measures, including the control of alcohol and tobacco consumption as well as changing dietary pattern, will reduce the incidence and mortality burden of digestive cancers in the Nordic countries.

Diabetes in relation to biliary tract cancer and stones: a population-based study in Shanghai, China

BACKGROUND

Biliary tract cancers are rare but fatal malignancies. Diabetes has been related to biliary stones, but its association with biliary tract cancers is less conclusive.

METHODS

In a population-based case-control study of 627 cancers, 1037 stones, and 959 controls in Shanghai, China, we examined the association between diabetes and the risks of biliary tract cancer and stones, as well as the effect of potential mediating factors, including serum lipids and biliary stones (for cancer), contributing to the causal pathway from diabetes to biliary diseases.

RESULTS

Independent of body mass index (BMI), diabetes was significantly associated with gallbladder cancer and biliary stones ((odds ratio (OR) (95% confidence interval)=2.6 (1.5-4.7) and 2.0 (1.2-3.3), respectively). Biliary stones and low serum levels of high-density lipoprotein (HDL) were significant mediators of the diabetes effect on gallbladder cancer risk, accounting for 60 and 17% of the diabetes effect, respectively. High-density lipoprotein was also a significant mediator of the diabetes effect on biliary stones, accounting for 18% of the diabetes effect.

CONCLUSIONS

Independent of BMI, diabetes is a risk factor for gallbladder cancer, but its effect is mediated in part by biliary stones and serum HDL levels, suggesting that gallbladder cancer risk may be reduced by controlling diabetes, stones, and HDL levels.

Reproductive factors and risks of biliary tract cancers and stones: a population-based study in Shanghai, China

BACKGROUND

Parity has been linked to gallbladder cancer and gallstones, but the effects of other reproductive factors are less clear.

METHODS

We examined 361 incident biliary tract cancer cases, 647 biliary stone cases, and 586 healthy women in a population-based study in Shanghai.

RESULTS

The effects of parity (odds ratios, OR(> or =3 vs 1 child)=2.0, 95% confidence interval (CI) 0.7-5.1), younger age at first birth (OR(per 1-year decrease)=1.2, 95% CI 0.99-1.6), and older age at menarche (OR(per 1-year increase)=1.4, 95% CI 1.1-1.8) on gallbladder cancer risk were more pronounced among women with stones, but the interactions were not significant.

CONCLUSION

Our results provide support for high parity, younger age at first birth, and late age at menarche in the development of gallbladder cancer, particularly among women with biliary stones.

Androgen receptor CAG repeat length and risk of biliary tract cancer and stones

Biliary tract cancers, encompassing cancers of the gallbladder, extrahepatic bile ducts, and ampulla of Vater, are rare but highly fatal. Gallstones represent the major risk factor for biliary tract cancer, and share with gallbladder cancer a female predominance and an association with reproductive factors and obesity. Although estrogens have been implicated in earlier studies of gallbladder cancer, there are no data on the role of androgens. Because intracellular androgen activity is mediated through the androgen receptor (AR), we examined associations between AR CAG repeat length [(CAG)(n)] and the risk of biliary tract cancers and stones in a population-based study of 331 incident cancer cases, 837 gallstone cases, and 750 controls from Shanghai, China, where the incidence rates for biliary tract cancer are rising sharply. Men with (CAG)(n) >24 had a significant 2-fold risk of gallbladder cancer [odds ratio (OR), 2.00; 95% confidence interval (CI), 1.07-3.73], relative to those with (CAG)(n) < or = 22. In contrast, women with (CAG)(n) >24 had reduced gallbladder cancer risk (OR, 0.69; 95% CI, 0.43-1.09) relative to those with (CAG)(n) < or = 22; P interaction sex = 0.01, which was most pronounced for women ages 68 to 74 (OR, 0.48; 95% CI, 0.25-0.93; P interaction age = 0.02). No associations were found for bile duct cancer or gallstones. Reasons for the heterogeneity of genetic effects by gender and age are unclear but may reflect an interplay between AR and the levels of androgen as well as estrogen in men and older women. Further studies are needed to confirm these findings and clarify the mechanisms involved.

Variants of DNA repair genes and the risk of biliary tract cancers and stones: a population-based study in China

Biliary tract cancers, which encompass tumors of the gallbladder, extrahepatic ducts, and ampulla of Vater, are relatively rare tumors with a high fatality rate. Other than a close link with gallstones, the etiology of biliary tract cancers is poorly understood. We conducted a population-based case-control study in Shanghai, China, to examine whether genetic variants in several DNA repair genes are associated with biliary tract cancers or biliary stones. Genomic DNA from 410 patients with biliary tract cancers (236 gallbladder, 127 bile duct, and 47 ampulla of Vater), 891 patients with biliary stones, and 786 healthy subjects randomly selected from the Shanghai population were genotyped for putative functional single nucleotide polymorphisms in four DNA repair genes (MGMT, RAD23B, CCNH, and XRCC3). Of the five single nucleotide polymorphisms examined, only one (MGMT EX5-25C>T, rs12917) was associated with biliary tract cancer. Independent of gallstones, subjects carrying the CT genotype of the MGMT EX5-25C>T marker had a significantly reduced risk of gallbladder cancer [odds ratio (OR), 0.63; 95% confidence interval (95% CI), 0.41-0.97; P = 0.02] and nonsignificant reduced risks of bile duct (OR, 0.61; 95% CI, 0.35-1.06) and ampulla of Vater (OR, 0.85; 95% CI, 0.39-1.87) cancers. However, this marker was not associated with biliary stones, and the other markers examined were not significantly associated with either biliary tract cancers or stones. Findings from this population-based study in Shanghai suggest that MGMT gene variants may alter susceptibility to biliary tract cancer, particularly gallbladder cancer. Confirmation in future studies, however, is required.

Body size and the risk of biliary tract cancer: a population-based study in China

Though obesity is an established risk factor for gall bladder cancer, its role in cancers of the extrahepatic bile ducts and ampulla of Vater is less clear, as also is the role of abdominal obesity. In a population-based case–control study of biliary tract cancer in Shanghai, China, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for biliary tract cancer in relation to anthropometric measures, including body mass index (BMI) at various ages and waist-to-hip ratio (WHR), adjusting for age, sex, and education. The study included 627 patients with biliary tract cancer (368 gall bladder, 191 bile duct, 68 ampulla of Vater) and 959 healthy subjects randomly selected from the population. A higher BMI at all ages, including early adulthood (ages 20–29 years), and a greater WHR were associated with an increased risk of gall bladder cancer. A high usual adult BMI (⩾25) was associated with a 1.6-fold risk of gall bladder cancer (95% CI 1.2–2.1, P for trend <0.001). Among subjects without gallstones, BMI was also positively associated with gall bladder cancer risk. Regardless of BMI levels, increasing WHR was associated with an excess risk of gall bladder cancer risk, with those having a high BMI (⩾25) and a high WHR (>0.90) having the highest risk of gall bladder cancer (OR=12.6, 95% CI 4.8–33.2), relative to those with a low BMI and WHR. We found no clear risk patterns for cancers of the bile duct and ampulla of Vater. These results suggest that both overall and abdominal obesity, including obesity in early adulthood, are associated with an increased risk of gall bladder cancer. The increasing prevalence of obesity and cholesterol stones in Shanghai seems at least partly responsible for the rising incidence of gall bladder cancer in Shanghai.

Geographic variation of gallbladder cancer mortality and risk factors in Chile: a population-based ecologic study

Chile's gallbladder cancer rates are among the highest in the world, being the leading cause of cancer deaths among Chilean women. To provide insights into the etiology of gallbladder cancer, we conducted an ecologic study examining the geographical variation of gallbladder cancer and several putative risk factors. The relative risk of dying from gallbladder cancer between 1985 and 2003 was estimated for each of the 333 Chilean counties, using a hierarchical Poisson regression model, adjusting for age, sex and geographical location. The risk of gallbladder cancer mortality was analyzed in relation to region, poverty, Amerindian (Mapuche) population, typhoid fever and access to cholecystectomy, using logistic regression analysis. There were 27,183 gallbladder cancer deaths, with age and sex-adjusted county mortality rates ranging from 8.2 to 12.4 per 100,000 inhabitants. Rates were highest in inland and southern regions. Compared to the northern-coast, the northern-inland region had a 10-fold risk (95% of confidence interval (95% CI): 2.4-42.2) and the southern-inland region had a 26-fold risk (95% CI: 6.0-114.2). Independent of region, other risk factors for gallbladder cancer included a high Mapuche population (Odds ratio (OR):3.9, 95% CI 1.8-8.7), high typhoid fever incidence (OR:2.9, 95% CI 1.2-6.9), high poverty (OR:5.1, 95% CI 1.6-15.9), low access to cholecystectomy (OR:3.9, 95% CI 1.5-10.1), low access to hospital care (OR:14.2, 95% CI 4.2-48.7) and high urbanization (OR:8.0, 95% CI 3.4-18.7). Our results suggest that gallbladder cancer in Chile may be related to both genetic factors and poor living conditions. Future analytic studies are needed to further clarify the role of these factors in gallbladder cancer etiology.

Oral contraceptives and the risk of all cancers combined and site-specific cancers in Shanghai

From 1998 to 1991, an in-person baseline interview was administered to approximately 267,400 female textile workers in Shanghai, China. The cohort was followed until July 2000 for incident cancer cases. Incidence rate ratios (RR) for 12 types of cancers in users of oral contraceptives (OCs) were calculated using Cox Proportional Hazards analysis. There was a reduced risk of uterine corpus cancer for women who had ever used OCs (RR = 0.68, 95% CI = 0.45-1.04) and a trend of decreasing risk with increasing duration of use (p = 0.015). There was an increased risk of colon cancer in women who had used OCs for 10 years or more (RR = 1.56, 95% CI = 1.01-2.40) and an increased risk of rectal cancer in women who had ever used OCs (RR = 1.31, 95% CI = 0.98-1.75), with a trend of increasing risk with increasing duration of use (p = 0.017), but these associations may have been due to uncontrolled confounding by physical activity or other non-causal factors. No associations were observed between OCs and the risk of all cancers combined or for any of the nine other cancers. It is unlikely that the use of OCs has contributed to the temporal trends in cancer incidence in China in recent decades.

Variants in inflammation genes and the risk of biliary tract cancers and stones: a population-based study in China

To evaluate the role of chronic inflammation in the development of gallstones and biliary tract cancer, we examined the risk associated with 62 single nucleotide polymorphisms (SNPs), in 22 inflammation-related genes, in a population-based case-control study conducted in Shanghai, China, where the incidence of biliary tract cancer has been increasing in recent decades. The study included 411 cases with biliary tract cancer (237 gallbladder, 127 extrahepatic bile duct, and 47 ampulla of Vater), 895 with biliary stones, and 786 controls randomly selected from the population. Unconditional logistic regression was used to calculate odds ratios and 95% confidence intervals for the association of individual SNPs and haplotypes with biliary stones and biliary tract cancer. Of the 62 SNPs examined, 14 were related to the risk of biliary cancer and stones. Specifically, variants in the IL8, IL8RB, RNASEL, and NOS2 genes were associated with biliary stones, whereas VEGF variants were associated with gallbladder cancer. Of the 10 genes with multiple SNPs from which we inferred haplotypes, only one IL8RB haplotype, consisting of 3 SNPs (rs2230054, rs1126579, and rs1126580), was associated with the risk of bile duct cancer (P = 0.003) and biliary stones (P = 0.02), relative to the most frequent haplotype. In summary, common variants in genes that influence inflammatory responses may predispose to gallstones and biliary tract cancer, suggesting the need for future studies into the immunologic and inflammatory pathways that contribute to biliary diseases, including cancer.

Serum lipid levels and the risk of biliary tract cancers and biliary stones: A population-based study in China

Biliary tract cancers, encompassing the gallbladder, extrahepatic bile ducts and ampulla of Vater, are rare but highly fatal malignancies. Gallstones, the predominant risk factor for biliary cancers, are linked with hyperlipidemia. As part of a population-based case-control study conducted in Shanghai, China, we examined the associations of serum lipid levels with biliary stones and cancers. We included 460 biliary cancer cases (264 gallbladder, 141 extrahepatic bile duct, and 55 ampulla of Vater), 981 biliary stone cases and 858 healthy individuals randomly selected from the population. Participants completed an in-person interview and gave overnight fasting blood samples. Participants in the highest quintile of triglycerides (>/=160 mg/dl) had a 1.4-fold risk of biliary stones (95% CI = 1.1-1.9), a 1.9-fold risk of gallbladder cancer (95% CI = 1.3-2.8), and a 4.8-fold risk of bile duct cancer (95% CI = 2.8-8.1), compared to the reference group (third quintile: 90-124 mg/dl). Participants in the lowest quintile of high-density lipoprotein (HDL) (<30 mg/dl) had a 4.2-fold risk of biliary stones (95% CI = 3.0-6.0), an 11.6-fold risk of gallbladder cancer (95% CI = 7.3-18.5), and a 16.8-fold risk of bile duct cancer (95% CI = 9.1-30.9), relative to the reference group (third quintile: 40-49 mg/dl). In addition, total cholesterol, low-density lipoprotein (LDL) and apolipoprotein A (apo A) were inversely associated with biliary stones; whereas low levels as well as high levels of total cholesterol, LDL, apo A and apolipoprotein B (apo B) were associated with excess risks of biliary tract cancers. Our findings support a role for serum lipids in gallstone development and biliary carcinogenesis.

Hepatitis B and C virus infection and the risk of biliary tract cancer: a population-based study in China

Emerging data suggest that chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may also play a role in extrahepatic bile duct cancers. To test the HBV hypothesis, we examined the relationship of HBV/HCV infection with risks of biliary tract cancer and biliary stones in a population-based case-control study conducted in Shanghai, China. Standard assays were used to detect HBV surface antigen (HBsAg) and antibodies against HBV core antigen (anti-HBc) and hepatitis C virus (anti-HCV) in sera from 417 patients with biliary tract cancers, 517 with biliary stones, and 762 healthy controls randomly selected from the population. Unconditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for each disease type. HBsAg seroprevalence was 7.3% among population controls and 14.2% among patients with extrahepatic bile duct cancer, resulting in a 2.4-fold risk of extrahepatic bile duct cancer (95% CI 1.2-4.5). No association was found for cancers of the gallbladder (prevalence 8.2%) or the ampulla of Vater (6.1%), or for stones in the gallbladder (10.1%) or bile duct (9.3%). Further adjustment for education, smoking, body mass index, diabetes and gallstones did not materially change the results. Prevalence of HCV infection in this population was low (2%), limiting our ability to detect an association with biliary diseases. In Shanghai, an HBV endemic area, chronic HBV infection was associated with a 2.4-fold risk of extrahepatic bile duct cancer. These results should be confirmed in other populations with varying risks of HBV and HCV infection.

Polymorphisms of genes in the lipid metabolism pathway and risk of biliary tract cancers and stones: a population-based case-control study in Shanghai, China

Biliary tract cancers, encompassing the gallbladder, extrahepatic bile duct, and ampulla of Vater, are uncommon yet highly fatal malignancies. Gallstones, the primary risk factor for biliary cancers, are linked with hyperlipidemia. We examined the associations of 12 single nucleotide polymorphisms of five genes in the lipid metabolism pathway with the risks of biliary cancers and stones in a population-based case-control study in Shanghai, China. We included 235 gallbladder, 125 extrahepatic bile duct, and 46 ampulla of Vater cancer cases, 880 biliary stone cases, and 779 population controls. Subjects completed an in-person interview and gave blood. Genotyping was conducted by TaqMan assay using DNA from buffy coats. The effects of APOE IVS1+69 (rs440446) and APOB IVS6+360C>T (rs520354) markers were limited to men. Men carrying the G allele of APOE IVS1+69 had a 1.7-fold risk of stones [95% confidence interval (95% CI), 1.2-2.4], a 1.8-fold risk of gallbladder cancer (95% CI, 1.0-3.3), a 3.7-fold risk of bile duct cancer (95% CI, 2.0-7.0), and a 4-fold risk of ampullary cancer (95% CI, 1.4-12.4). Male carriers of the T allele of APOB IVS6+360C>T had a 2-fold risk of bile duct cancer (95% CI, 1.2-3.4). The APOB T-T haplotype (APOB IVS6+360C>T, EX4+56C>T) was associated with a 1.6-fold risk of bile duct cancer (95% CI, 1.1-2.3). Male and female carriers of the T allele of LDLR IVS9-30C>T (rs1003723) had a 1.5-fold risk of bile duct cancer. Our findings suggest that gene variants in the lipid metabolism pathway contribute to the risk of biliary tract stones and cancers, particularly of the bile duct.

Gallstones and the risk of biliary tract cancer: a population-based study in China

We conducted a population-based study of 627 patients with biliary tract cancers (368 of gallbladder, 191 bile duct, and 68 ampulla of Vater), 1037 with biliary stones, and 959 healthy controls randomly selected from the Shanghai population, all personally interviewed. Gallstone status was based on information from self-reports, imaging procedures, surgical notes, and medical records. Among controls, a transabdominal ultrasound was performed to detect asymptomatic gallstones. Gallstones removed from cancer cases and gallstone patients were classified by size, weight, colour, pattern, and content of cholesterol, bilirubin, and bile acids. Of the cancer patients, 69% had gallstones compared with 23% of the population controls. Compared with subjects without gallstones, odds ratios associated with gallstones were 23.8 (95% confidence interval (CI), 17.0–33.4), 8.0 (95% CI 5.6–11.4), and 4.2 (95% CI 2.5–7.0) for cancers of the gallbladder, extrahepatic bile ducts, and ampulla of Vater, respectively, persisting when restricted to those with gallstones at least 10 years prior to cancer. Biliary cancer risks were higher among subjects with both gallstones and self-reported cholecystitis, particularly for gallbladder cancer (OR=34.3, 95% CI 19.9–59.2). Subjects with bile duct cancer were more likely to have pigment stones, and with gallbladder cancer to have cholesterol stones (P<0.001). Gallstone weight in gallbladder cancer was significantly higher than in gallstone patients (4.9 vs 2.8 grams; P=0.001). We estimate that in Shanghai 80% (95% CI 75–84%), 59% (56–61%), and 41% (29–59%) of gallbladder, bile duct, and ampulla of Vater cancers, respectively, could be attributed to gallstones.

Family history of gallstones and the risk of biliary tract cancer and gallstones: a population-based study in Shanghai, China

Cancers of the biliary tract arise from the gallbladder, extrahepatic bile ducts and ampulla of Vater. Although relatively uncommon, the incidence of biliary tract cancer rose more than 100% in Shanghai, China between 1972 and 1994. Gallstones are the predominant risk factor for biliary tract cancers, with over 60% of the cancer cases having gallstones. A familial tendency to gallstones has been reported and may elevate the risk of gallbladder cancer further. As part of a large population-based case-control study of biliary tract cancers in Shanghai, China, we examined the association between a family history of gallstones and biliary tract cancers as well as biliary stones. A total of 627 biliary tract cancers (368 gallbladder, 191 bile duct, 68 ampulla of Vater), 1,037 biliary stone cases (774 gallbladder, 263 bile duct) and 959 healthy subjects randomly selected from the population were included in this study. Information on family history of gallstones among first-degree relatives (i.e., parents, siblings, offspring) was obtained through a self-reported history during in-person interviews. A family history of gallstones was associated with increased risks of biliary stones [odds ratio (OR) = 2.8, 95% confidence interval (CI) = 2.1-3.8], gallbladder cancer (OR = 2.1, 95% CI = 1.4-3.3) and bile duct cancer (OR = 1.5, 95% CI = 0.9-2.5), after adjustment for age, gender, marital status, education, smoking, alcohol drinking and body mass index. For gallbladder cancer, subjects with gallstones but without a family history of gallstones had a 21-fold risk (95% CI 14.8-30.1), while those with both gallstones and a positive family history had a 57-fold risk (95% CI 32.0-110.5). Significant risks for gallbladder cancer persisted after additional adjustment for gallstones, and when the analysis was restricted to subjects with first-degree relatives whose gallstones were treated with cholecystectomy. The significant associations with a family history of gallstones were seen for all first-degree relatives, including parents, siblings and offspring, but not spouses. This large population-based study not only supports the role of gallstones in biliary carcinogenesis but also suggests that the underlying genetic or lifestyle determinants of stones within families contribute to the risk of biliary tract cancer.

A meta-analysis of occupational trichloroethylene exposure and liver cancer

OBJECTIVE

Findings from epidemiologic studies of trichloroethylene (TCE) exposure and liver cancer have been inconsistent. To quantitatively evaluate this association and to examine sources of heterogeneity, we conducted a meta-analysis of occupational studies of TCE exposure and liver/biliary tract cancer.

METHODS

We identified 14 occupational cohort studies of TCE exposed workers and one case-control study that met our inclusion criteria. Nine studies specifically identified TCE as a workplace exposure, and were classified as Group I cohort studies. Subcohorts of workers, identified within eight of these studies as more likely exposed to TCE than the total cohort, were analyzed separately.

RESULTS

The combined liver/biliary cancer summary relative risk estimate (SRRE) for all studies was 1.08 (95% CI 0.91-1.29; heterogeneity (H)-P-value=0.12). For the total study populations in the Group I cohorts, the SRRE was 1.14 (95% CI 0.93-1.39; H-P-value=0.05) and for the subcohorts, the SRRE was 1.30 (95% CI 1.09-1.55). Within this subcohort analysis, the association for the European studies of workers from various industries (SRRE=1.38; based on four studies) was higher than the association for the US studies of aerospace and aircraft workers (SRRE=0.97, based on four studies).

CONCLUSION

Although positive associations were observed for some analyses, results were inconsistent across occupational groups (aerospace/aircraft vs. other industries combined), study location, and incidence versus mortality endpoints. In addition, exposure-response trends were not observed consistently across studies. Interpretation is also limited by the potential impact of uncontrolled confounding by other occupational or lifestyle exposures such as smoking or alcohol consumption. Given these limitations, the currently available epidemiologic data are not sufficient to support a causal relation between occupational TCE exposure and liver/biliary cancer.

Biliary tract cancer and stones in relation to chronic liver conditions: A population-based study in Shanghai, China

Biliary tract cancers are relatively rare but fatal tumors. Apart from a close link with gallstones and cholangitis, risk factors for biliary tract cancer are obscure. Chronic liver conditions, including liver cirrhosis, have been linked to a higher risk of biliary tract cancer. In a population-based case-control study conducted in Shanghai, China, we investigated the relationships of a history of chronic hepatitis and liver cirrhosis as well as a family history of liver cancer with biliary tract cancer risk. The study included 627 patients with biliary tract cancers (368 gallbladder, 191 bile duct and 68 ampulla of Vater), 1,037 patients with biliary stones (774 gallbladder stones and 263 bile duct stones) and 959 healthy subjects randomly selected from the population. Bile duct cancer was associated with self-reports of chronic liver conditions, including a history of chronic hepatitis (OR = 2.0, 95% CI 0.9-4.4), liver cirrhosis (OR = 4.7, 95% CI 1.9-11.7) and a family history of primary liver cancer (OR = 2.0, 95% CI 1.0-3.9). The excess risk persisted after adjustment for gallstones and were more pronounced among subjects without gallstones (OR = 5.0, 95% CI 1.3-20.0 and OR = 4.9, 95% 2.0-12.2, respectively). History of liver conditions was also associated with an excess of biliary stones (OR = 1.9, 95% CI 1.2-3.0). No association was found for cancers of the gallbladder and ampulla of Vater. A history of chronic hepatitis and cirrhosis may be risk factors for extraheptic bile duct cancer. Given that chronic infection with hepatitis B virus (HBV) is the most common cause of liver disease in China, serologic markers of HBV need to be measured in future studies to examine the link between HBV and bile duct cancer.

Prostaglandin-endoperoxide synthase 2 (PTGS2) gene polymorphisms and risk of biliary tract cancer and gallstones: a population-based study in Shanghai, China

There is evidence that chronic inflammation predisposes to biliary tract cancer and that use of non-steroidal anti-inflammatory drugs (NSAIDs) is protective. Although the mechanisms by which NSAIDs lower cancer risk remain unclear, NSAIDs reduce prostaglandin production by blocking prostaglandin-endoperoxide synthase 2 (PTGS2, commonly known as COX-2), an enzyme induced by proinflammatory stimuli that is often overexpressed in malignant tissue. Since variants in the PTGS2 gene may modify the expression or function of its encoded enzyme to modulate the inflammatory response in the biliary tract, we examined the associations of eight PTGS2 polymorphisms (-645C-->T; Ex3 -8G-->C; IVS5 -275T-->G; IVS7 +111T-->C; Ex10 +127T-->C; Ex10 +686 --->ATTAT-->TTATA; Ex10 +837T-->C; Ex10 -90C-->T) with biliary tract cancer and stones in a population-based case-control study conducted in Shanghai, China. Genotyping was performed for 411 patients with biliary tract cancer (237 gallbladder, 127 extrahepatic bile duct and 47 ampulla of Vater), 895 patients with biliary stones (673 gallbladder, 222 bile duct), and 786 healthy individuals randomly selected from the population. Significant associations were seen only between the Ex10 +837T-->C marker and bile duct cancer risk. Relative to individuals with the TT genotype, those carrying the C allele (TC or CC genotype) had a 1.8-fold (95% confidence interval: 1.2-2.7) risk of bile duct cancer. Inferred haplotypes including this risk-conferring allele were also associated with increased bile duct cancer risk of similar magnitude. Our results suggest that a common PTGS2 variant increases bile duct cancer risk. Further investigation is needed to confirm and extend our findings in studies of biliary tract cancer that more comprehensively examine PTGS2 and other inflammation-related genes.