Correlates of liver cancer mortality in China

A systematic review and meta-analysis of the association between vitamin A intake, serum vitamin A, and risk of liver cancer

BACKGROUND

Previous evidence supports that vitamin A decreases the risk of several types of cancer. However, the association between vitamin A and liver cancer is inconclusive.

AIM

This systematic review and meta-analysis summarizes the existing literature, discussing the association between vitamin A intake, serum vitamin A, and liver cancer in adult populations.

METHODS

A systematic literature review was performed by searching the EMBASE, PubMed, Scopus and International Pharmaceutical Abstract databases using terms related to vitamin A (e.g. retinol, α-carotene, β-carotene, and β-cryptoxanthin) and hepatic cancer without applying any time restriction. A meta-analysis was performed using random effect models.

RESULTS

The meta-analysis of five studies showed no association between serum retinol and liver cancer (pooled risk ratio = 1.90 (0.40-9.02); n = 5 studies, I² = 92%). In addition, the systematic review of studies from 1955 to July 2017 found studies that indicated no association between the intake and serum level of α-carotene ( n = 2) and β-cryptoxanthin ( n = 1) and the risk of liver cancer. Further, the associations between retinol intake ( n = 3), β-carotene intake ( n = 3), or serum β-carotene ( n = 3) and liver cancer were inconclusive.

CONCLUSIONS

Current information on the association between vitamin A intake and liver cancer or serum vitamin A and liver cancer are limited. Most studies demonstrated no association between dietary vitamin A and the risk of liver cancer. However, the finding was based on a small number of studies with potential publication bias. Therefore, large observational studies should be conducted to confirm these associations.

Hepatocellular carcinoma epidemiology

Primary liver cancer (namely hepatocellular carcinoma, HCC) is worldwide the fifth most common cancer in men and the seventh one in women, and it represents the third most frequent cause of cancer death. HCC rates are particularly high in eastern/south-eastern Asia and in Africa, intermediate in Southern Europe, and low in most high-income countries. Persistent infections by HBV or HCV are the main recognized risk factors for HCC. Aflatoxin exposure is also an important risk factor for HCC development in Africa and eastern Asia. In high-income countries heavy alcohol drinking, tobacco smoking, overweight, diabetes, familial/genetic factors, and selected dietary aspects, have a relevant role. Updated geographic patterns and time trends in mortality from HCC in Europe, USA, Japan, and Australia are provided in the present review, together with an overview of relevant etiologic factors for HCC and main measures for the prevention of this neoplasm.

Vegetable-based dietary pattern and liver cancer risk: results from the Shanghai women's and men's health studies

Although dietary patterns, specific foods, and their constituents have been linked to cancer risk, the role of dietary patterns and specific food groups in liver cancer risk has not been investigated. In the Shanghai Women's Health Study (SWHS) and Shanghai Men's Health Study (SMHS), two cohort studies of 132 837 Chinese women and men, we evaluated the relationship between dietary patterns, food groups, and liver cancer risk. Through in-person interviews, dietary information intake over the preceding year was collected by using a validated food-frequency questionnaire. Cox regression model was used to estimate hazard ratios and 95% confidence intervals with adjustment for potential confounders. During an average follow-up of 10.9 (SWHS) or 5.5 (SMHS) years, 267 incident liver cancer cases were identified after the first 2 years of study enrolment. Three dietary patterns were derived by factor analysis. A vegetable-based dietary pattern was inversely associated with liver cancer; hazard ratios (95% confidence intervals) for the lowest to highest quartiles were: 1.00; 0.98 (0.71-1.35); 0.93 (0.67-1.29); and 0.58 (0.40-0.84); P(trend) = 0.01. The association was stronger among participants with a history of chronic liver disease. Further analyses showed high intakes of celery, mushrooms, allium vegetables, composite vegetables (including asparagus lettuce and garland chrysanthemum), legumes and legume products were associated with reduced liver cancer risk (all P(trend) < 0.05). Fruit- and meat-based dietary patterns were not associated with liver cancer risk. Our study suggests that a vegetable-based dietary pattern is associated with reduced liver cancer risk.

Hepatitis B and C virus infection and hepatocellular carcinoma in China: a review of epidemiology and control measures

China has one of the highest carrier prevalences of hepatitis B virus (HBV) in the world: nearly 10% of the general population. The disease burden of HBV infection and hepatocellular carcinoma (HCC) is also believed to be among the world's largest, and that of hepatitis C virus (HCV) infection is likely to be substantial as well. However, the epidemiology and measures to control HBV and HCV infection in China remain relatively unknown outside the country. We review the epidemiology of HBV and HCV infection, the disease burden of and risk factors for HCC, and current control measures against HBV and HCV infection in China. We also discuss the relevant literature and implications for future studies of hepatitis and HCC in China.

Hepatitis B and C virus infection and hepatocellular carcinoma in China: a review of epidemiology and control measures

China has one of the highest carrier prevalences of hepatitis B virus (HBV) in the world: nearly 10% of the general population. The disease burden of HBV infection and hepatocellular carcinoma (HCC) is also believed to be among the world’s largest, and that of hepatitis C virus (HCV) infection is likely to be substantial as well. However, the epidemiology and measures to control HBV and HCV infection in China remain relatively unknown outside the country. We review the epidemiology of HBV and HCV infection, the disease burden of and risk factors for HCC, and current control measures against HBV and HCV infection in China. We also discuss the relevant literature and implications for future studies of hepatitis and HCC in China.

Interactions between cigarette and alcohol consumption in rural China

The objective of this paper is to analyze interdependencies between cigarette and alcohol consumption in rural China, using panel data for 10 years (1994-2003) for rural areas of 26 Chinese provinces. There have been many studies in which cigarette and alcohol consumption have been considered separately but few to date for China on interactions between the consumption of these two products. Taxes are often recommended as a tool to reduce alcohol and cigarette consumption. If cigarettes and alcohol are complements, taxing one will reduce the consumption of both and thus achieve a double public health dividend. However, if they are substitutes, taxing one will induce consumers to increase consumption of the other, offsetting the public health benefits of the tax. Our results indicate that the demands for both cigarettes and alcohol are very sensitive to the price of alcohol, but not to the price of cigarettes or to income. This suggests that taxes on alcohol can have a double dividend. On the other hand, an increase in cigarette taxes may not be effective in curbing cigarette or alcohol consumption in rural China.

Food groups and risk of hepatocellular carcinoma: A multicenter case-control study in Italy

The role of diet, except for alcohol drinking and aflatoxin contamination, in the etiology of hepatocellular carcinoma (HCC) is unclear. A hospital-based case-control study was conducted in Italy in 1999-2002, including 185 incident, histologically-confirmed cases of HCC. Controls were 412 subjects admitted to hospitals for acute, nonneoplastic diseases unrelated to diet. Dietary habits were assessed using a validated food-frequency questionnaire. Odds ratios (ORs) and the corresponding 95% confidence intervals (CI) were computed using unconditional multiple logistic regression, adjusting for hepatitis B (HBV) and hepatitis C (HCV) virus infection and alcohol drinking. Energy adjustment was carried out by means of the residual model. A significant inverse relation was found between intakes of milk and yoghurt (OR = 0.28; 95% CI: 0.13-0.61), white meats (OR = 0.44; 95% CI: 0.20-0.95), eggs (OR = 0.31; 95% CI: 0.14-0.69), and fruits (OR = 0.48; 95% CI: 0.22-1.05) and HCC risk. The favourable effect of high intakes of milk and yoghurt, white meats, eggs and fruits was consistent across strata of HBV and HCV infections. The present study supports the hypothesis of a role of diet in HCC aetiology. Dietary modifications may be indicated in subjects at high-risk for HCC.

Toenail selenium and risk of hepatocellular carcinoma mortality in Haimen City, China

Selenium (Se) is an essential trace mineral with known anticarcinogenic properties in humans. However, few studies have examined the association between Se nutrient status and risk of liver cancer. We conducted a nested case-control study comparing the Se content in toenail clippings of 166 individuals (154 men, 12 women) with hepatocellular carcinoma (HCC) to 394 healthy controls (360 men, 34 women) in Haimen City, China, where HCC is a leading cause of mortality. Toenail Se concentration was measured by inductively coupled plasma-optical emission spectroscopy. Median toenail Se was lower for HCC cases than controls (p = 0.03). Adjusted odds ratios and 95% confidence intervals for HCC mortality by increasing quartile of toenail Se were 1.00 (reference), 0.58 (0.32-1.03), 0.83 (0.48-1.42) and 0.50 (0.28-0.90), with a marginally significant trend in risk observed (p for trend = 0.06). This inverse association appeared stronger among those who did not consume alcohol and among women. Future studies are needed to examine the interrelationship between Se, viral hepatitis infection and HCC in order to better understand the etiologic mechanisms involved and evaluate the true chemopreventive potential of Se compounds for liver diseases.

Epidemiology and natural history of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major contributor to cancer incidence and mortality. There is a wide variation, however, in the global distribution of HCC. Eighty percent of the burden is borne by countries in Asia and sub-Saharan Africa. In most high-risk countries, principal risk factors include infection with hepatitis B virus and dietary exposure to aflatoxin B(1). In contrast, hepatitis C virus and alcohol consumption are more important risk factors in low-risk countries. In recent years, the incidence of HCC has decreased in some high-risk countries and increased in some low-risk countries. Reasons for both trends are not completely understood, but are likely related to public health efforts in Asia and the increase in hepatitis C virus infection in low-risk countries. Vaccination programs against hepatitis B virus will likely decrease the HCC rate even further in decades to come.

Short- and intermediate-term carcinogenicity testing--a review. Part 1: the prototypes mouse skin tumour assay and rat liver focus assay

Carcinogenicity testing is by far the most expensive and time-consuming study type of toxicology. For many years, the lifetime exposure with the maximum tolerated dose in two rodent species has been the gold standard of carcinogenicity testing of pharmaceuticals. Major change was introduced by the Fourth International Conference on Harmonization in July 1997; a chronic rodent bioassay in one species and a short-term carcinogenicity assay are regarded as sufficient for registration. Such requirements provide the opportunity to redirect the vast resources previously spent on the lifetime study in the second species. Numerous experimental protocols for short- and intermediate-term carcinogenicity testing in many target tissues have been available for years. The first part of this review describes the basic principles of short- and intermediate-term carcinogenicity testing using the examples of the widely used mouse skin tumour assay and the rat liver foci assay. In the context of these experimental models, the discrimination and quantification of initiating and promoting activity and the use of preneoplastic lesions as endpoints in carcinogenicity testing are described. The review includes the limitations of the models with regard to the extrapolation from effects observed in animal experiments to a potential exposure of humans.

Serum copper and zinc concentrations in serum from patients with cancer and cardiovascular disease

A single cross-sectional study for serum copper and zinc levels was evaluated in 20 patients with cancer (respiratory, digestive, haematological, gynaecological) and 21 patients with cardiopathy (acute myocardial infarction and ischemic cardiomyopathy). A control group of 84 healthy subjects was selected. The mean serum zinc levels in patients with gynaecological cancer and ischemic cardiomyopathy were significantly lower than the control group (P < 0.05). However, the mean serum copper level was not statistically different among patients with cancer (P < 0.05) and cardiomyopathy (P > 0.05) than the control group. Male patients did not have statistically different values for serum Cu (P > 0.05) and Zn (P < 0.05) than those found in female patients. Patients' age did not have any statistical influence (P > 0.05) on serum Cu and Zn levels.

Cellular interactions and metabolism of aflatoxin: an update

The aflatoxins are a group of closely related mycotoxins that are widely distributed in nature. The most important of the group is aflatoxin B1 (AFB1), which has a range of biological activities, including acute toxicity, teratogenicity, mutagenicity and carcinogenicity. In order for AFB1 to exert its effects, it must be converted to its reactive epoxide by the action of the mixed function mono-oxygenase enzyme systems (cytochrome P450-dependent) in the tissues (in particular, the liver) of the affected animal. This epoxide is highly reactive and can form derivatives with several cellular macromolecules, including DNA, RNA and protein. Cytochrome P450 enzymes may additionally catalyse the hydroxylation (to AFQ1 and AFM1) and demethylation (to AFP1) of the parent AFB1 molecule, resulting in products less toxic than AFB1. Conjugation of AFB1 to glutathione (mediated by glutathione S-transferase) and its subsequent excretion is regarded as an important detoxification pathway in animals. Resistance to AFB1 toxicity has been interpreted in terms of levels and activities of these detoxifying pathways. This article reviews the multiple reactions and effects attributed to aflatoxin, with particular reference to the interaction of aflatoxin with nucleic acids and proteins, and the contribution this mycotoxin has in disease development and in the promotion of hepatocellular carcinoma (HCC). The anti-mutagenic properties of several dietary factors are also considered in this article. Undoubtedly, the most important aspect of aflatoxin action is its putative role in the development of human cancer, in particular, HCC. Recently, there has been a renewed interest in this aspect and experimental evidence is rapidly accumulating at the molecular level, indicating aflatoxin as an important consideration in the aetiology of human HCC.

Primary hepatocellular carcinoma in aboriginal Australians

We identified incident cases of primary hepatocellular carcinoma (PHC) in the Northern Territory from 1980 to 1989: there were 18 Aboriginal and six non-Aboriginal cases, yielding incidence rates of 5.2 per 100,000 (Aboriginal) and 0.5 per 100,000 (non-Aboriginal) with a relative risk of 10.4 (95 per cent confidence interval (CI) 4.0 to 26.6). The carcinoma was more frequent in males (2.3 per 100,000) than in females (0.7 per 100,000), with a relative risk of 3.4 (CI 1.3 to 9.3). Incidence increased with age; the trend was statistically significant in Aborigines (chi 2(1) = 4.7, P < 0.05) but not in non-Aborigines (chi 2(1) = 3.4, P > 0.05). Hepatitis B virus (HBV) serology was available for 11 Aboriginal and four non-Aboriginal cases; seven of the Aboriginal cases and two of the non-Aboriginal cases were positive for hepatitis B surface antigen (HBsAg). The prevalence of HBsAg in Aboriginal patients with the carcinoma (63.6 per cent) was much higher than that (13.1 per cent) in Aborigines surveyed from communities in the Northern Territory (chi 2(1) = 21.7, P < 0.001). Our results show that the age-specific incidence of PHC in Aborigines in the Northern Territory (30.9 for ages 40 and over) is comparable to that in high-incidence countries such as China (36.9 for ages 40 and over), and that hepatitis B is of major aetiological importance in the Aboriginal population. This underlines the importance of universal immunisation for prevention of HBV infection and for long-term prevention of PHC.

Diet and blood nutrient correlations with ischemic heart, hypertensive heart, and stroke mortality in China

Though major differences exist in subcategory mortality levels, cardiovascular disease remains a leading cause of death among both Asian Chinese and Westerners. This paper examines the possible relationship between cardiovascular mortality and biochemical, diet and lifestyle factors based on two surveys in China. Statistically significant associations indicate five variables negatively correlated: molybdenum, oleic acid, liquor consumption (males), legumes, and age at first pregnancy with ischemic heart disease; molybdenum, oleic acid (females) and age at first pregnancy with hypertensive heart disease; and legumes and age at first pregnancy with stroke. Five variables were positively correlated: triglycerides and herpes antibodies with ischemic heart disease; salt and phosphorus (females) with hypertensive heart disease; and only albumin (males) with stroke. Some findings confirm those observed in the West (salt, triglycerides, herpes, legumes, oleic acid, and liquor), but molybdenum and age at first pregnancy have not been emphasized previously. Still others significant in the West have not been observed here, such as cholesterol and smoking.

Occupational risks for primary liver cancer in Shanghai, China

Using occupational data for over 3,400 primary liver cancer cases diagnosed between 1980 and 1984 reported to the Shanghai Cancer Registry, and employment information from the 1982 census for the Shanghai population, standardized incidence ratios were computed to generate leads to occupational risks of liver cancer. Among men, a statistically significant excess number of cases was observed for chemical processors, textile workers, wood workers, blacksmiths and machine-tool operators, and material handlers and dock workers. Increased incidence of liver cancer also was observed among female transport equipment operators. These findings indicate that a number of similar occupations are associated with increased risk of primary liver cancer in western countries and China. Although causal inferences cannot be drawn from these data, our study adds to the limited evidence of the potential role of occupational exposures in liver carcinogenesis.