Liver cancer, epidemiology

Novotna E, David A, Malek B. 1979. [An epidemiological study of hepatic tumor incidence in subjects working with trichloroethylene. I. Negative result of retrospective investigations in subjects with primary liver cancer. ] Prac Lek 31 121-123. (Czech)... 

In contrast to animal studies, epidemiological studies of workers employed in the manufacture of aldrin provide no conclusive evidence of carcinogenicity in humans. " One study of a cohort having mixed exposure to aldrin, dieldrin, and endrin found 9 deaths from cancer versus 12 expected. The workers had been exposed to the pesticides for a mean of 11 years and followed a mean of 24 years. A more recent examination of 2384 manufacturing workers, employed between 1952 and 1982, with exposure to a number of pesticides including aldrin found no excess mortality rates attributable to occupational exposures. Similarly, a 2 3-year follow-up of 570 aldrin- and dieldrin-exposed workers found no increase in overall mortality rates or mortality from liver cancer."... 

Harden, L., Bengtsson, N.O., Jonsson, U., Erikssonn, S. Larsson, L.G. (1984) Aetiological aspects of primary liver cancer with special regard to alcohol, organic solvents and acute intermittent porphyria—an epidemiological investigation. Br. J. Cancer. 50, 389-397... 

Biomarkers can also be used to identify factors that increase the likelihood that an individual will develop disease. This is an important area of research in molecular epidemiology as it becomes more evident that not all risk factors will contribute to disease equally across the human population. Therefore, in order to determine whether an environmental agent is related to disease, those factors that are also required for disease development need to be taken into account. Otherwise, many disease risk factors may go undetected. Examples of susceptibility factors that can be ascertained using biomarkers are some viral infections, which may predispose to specific diseases (for example, HIV infection and Kaposi sarcoma) or HBV infection and liver cancer. Biomarkers can also be used to measure dietary factors that can contribute to disease. The most common susceptibility factor studied using a molecular epidemiological approach are hereditary factors, which are discussed in the following section. 

P. Scholl J. D. Groopman, Epidemiology of Human Aflatoxin Exposures and its Relationship to Liver Cancer. In Molecular Approaches to Food Safety Issues Involving Toxic Microorganisms, M. Eklund, J. L. Richard, K. Mise, Eds. Alaken, Inc. Fort Collins, CO, 1995 pp 169-182. 

The aflatoxins are a group of related mycotoxins produced by the mould Aspergillus flavus. There are four toxins, B, B2, G, and G2. The mould typically grows on crops such as grain and peanuts in hot, humid climates. There is evidence from epidemiology of an association between exposure to aflatoxin Bi in the diet and liver cancer in humans. Aflatoxin Bj is metabolized by the enzyme system cytochrome P450 in the liver to a chemically reactive metabolite (see pp. 19-23 and fig. 25), which reacts with molecules such as DNA and protein in liver cells. 

Qian G-S, Ross RK, Yu MC, et al. (1994) A follow-up study of urinary markers of aflatoxin exposure and liver cancer risk in Shanghai, People s Republic of China. Cancer Epidemiology, Biomarkers and Prevention 3 3-10. 

Bosch F, Ribes J, Borras J. Epidemiology of primary liver cancer. Semin Liver Dis 1999 19 271-85. 

The role of Schistosoma japonicum in cancer occnrrence is less clear, although this parasite has been associated with both liver and colorectal cancer. Some epidemiological and clinical stndies in China and Japan snpport its role as one of the risk factors in HCC formation. Experimental stndies have shown that liver cancer appears early in experimentally S. japonicum infected animals (Khurana et al. 2005). 

Although aflatoxin has been shown to be toxic to humans (22), the role of these toxins in human primary liver cancer remains obscure. Epidemiological studies in humans conducted in portions of Africa show a correlation between increased incidence of human primary liver cancer and increase in aflatoxin intake (23). However, epidemiological studies in the U.S. do no indicate a correlation between incidence of primary human liver cancer and aflatoxin consumption. In the Southeast, the average intake of aflatoxin is estimated to be nine times greater than the national average (24). However, according to unpublished data from the... 

Using epidemiological methods, the relationship between aflatoxln exposure and human liver cancer has been hindered by inadequate data on aflatoxln consumption, excretion, metabolism, and the general poor quality of world-wide cancer morbidity and mortality statistics. Molecular dosimetry methods are needed to help accurately assess an individual s exposure to aflatoxins. This is especially important because of the recent reclassification by the... 

Extensive literature reviews of the aflatoxin field have been published and the reader should refer to the following recent reviews that describe the toxicology (2) biological monitoring (3) and epidemiological aspects of aflatoxins and liver cancer (4) for more complete descriptions of research in these areas. 

This four year molecular epidemiological study in The Geunbia will help elucidate the role of hepatitis B virus and aflatoxins in the etiology of liver cancer by the analysis and quantitation of specific biomarkers. Both seasonal and... 

Summary Primary hepatocellular carcinoma is one of the most common cancers in the world and is prevalent on the continents of Africa and Asia. A number of classical epidemiological studies have determined that the exposure status of people to aflatoxin B1 is an important risk factor in the etiology of liver cancer. However, these studies have only relied upon the criteria of presumptive intake data, rather than information obtained from quantitative analyses of food samples, biological fluids and from people exposed to aflatoxin. Information obtained by monitoring exposed individuals for specific DNA adducts and metabolites will define the pharmacokinetics of aflatoxin B1 in people, thereby facilitating risk assessments. Preliminary data, reported here, support the concept that measurement of the major, rapidly excised AFB-N7-Gua adduct in urine and quantification of the more persistent aflatoxin albumin adduct are appropriate dosimeters for estimating exposure status and possibly risk in individuals consuming this mycotoxin. 

Epidemiological studies Implicate AF as of importance in the induction of liver cancer in man, particularly in certain parts of the world (e.g. South-east Asia and sub-Saharan Africa), however, it is not evident whether this carcinogen induces cancer alone or through an interaction with hepatitis B virus (HBV) infection (4). Although human exposure to NNO is well documented (see 3, 5), it is not evident which human cancer(s) could be directly attributed to this group of compounds. 

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