Showing papers by "International Agency for Research on Cancer published in 1972"

Esophageal Cancer in the Caspian Littoral of Iran: Initial Studies

Abstract: A peculiar distribution of esophageal cancer was observed in the Caspian littoral of Iran, where an ad hoc cancer registry has been in operation since 1968. A very high incidence, among the hghest recorded in the world, with a higher incidence in women than in men (male: 108.8 cases per 100,000 population; female: 174.1 per 100,000), was recorded in the northeastern corner of the region; this sparsely populated, semidesert area of the central Asian type, with predominantly saline soils, was settled by Turkomans. A lower incidence with a change in the male-to-female ratio was observed in the southeastern and central parts of the region, which are located in the piedmont area of the Elburz Mountains; these areas have more abundant rainfall and nonsaline soils, and are densely populated by Iranians. A steady decline in the incidence with an increase in the preponderance of male cases was observed toward the west, reaching the lowest figures (male: 17.2 cases per 100,000 population; female: 5.5 per 100,000) in the Caspian rain belt, with its heavily leached soils and somewhat subtropical characteristcs. Changes in the natural vegetation and in the agricultural practices parallel the changing features of the climate. A multidisciplinary, multidisease, and multifactorial study is in preparation. By plotting the detailed physical, biotic, and cultural characteristics of the selected ecological regions on the intrinsic characteristics of the population groups experiencing different esophageal cancer risk, new and profitable working hypotheses as to the etiology of esophageal cancer might be produced.

The effect of long-term exposure to DDT on CF-1 MICE.

Abstract: CF-1 minimal inbred mice were given technical DDT mixed into the diet at the dose levels of 2, 10, 50 and 250 parts per million (ppm) for the entire life span for two consecutive generations. Exposure to all four levels of DDT resulted in a significant increase of liver tumours in males, this being most evident at the highest level used. In females, the incidence of liver tumours was slightly increased following the exposure to 10 and 50 ppm, while a marked increase was observed following exposure to 250 ppm. In DDT-treated animals the liver tumours were observed at an earlier age than in untreated controls. The age at death with liver tumours and the incidence of liver tumours appeared to be directly related to the dose of DDT to which the mice were exposed. Four liver tumours, all occurring in DDT-treated mice, gave metastases. Histologically, liver tumours were either well-differentiated nodular growths, pressing but not infiltrating the surrounding parenchyma, or nodular growths in which the architecture of the liver was obliterated showing glandular or trabecular patterns.

Histological Types of Gastric Cancer and its Relationship with Intestinal Metaplasia

Abstract: There are two striking features in the epidemiology of gastric cancer. First, the great variation in the incidence of gastric cancer, which has been described from country to country, and also within a given country from one area to another. High rates have been reported for Japan, Finland, Iceland, Poland and mountainous regions of Colombia and Slovenia, and low rates for the Caucasian population of the United States, New Zealand, some African countries and littoral areas of Colombia and Slovenia [1–4]. Second, the persistent decline in gastric cancer rates which has been described in many countries [5–6]. In an attempt to determine if a particular histological type of gastric carcinoma is responsible for these striking features, a modification of the histological classification proposed by LAUREN [4, 7–8] has been used to classify gastric cancer cases from different geographic areas.

Dependence of the specificity of the serologic test for primary liver cancer in different areas of the world on sensitivity of the method used for detecting alpha-fetoprotein.

Abstract: A comparative investigation was made of the diagnostic value of the AFP test as dependent on sensitivity of the method used for detecting AFP. Patients' sera, collected from five African countries, from Singapore, Jamaica, and the USSR, and checked earlier by the standard AFP test (agar-gel precipitation technique) were reexamined using the method of indirect immunoradioautography. The latter method is 30 to 50 times more sensitive than the standard AFP test. As a result the percentage of hepatomas revealed serologically was increased for Africa from 75% to 89.2% and for the USSR from 64% to 87.1% (among histologically proven cases). The diagnostic specificity of the test became significantly lower: a great number of AFP-positive cases was observed in the control group. The proportion of such “false-positive” cases is not equal in different parts of the world: 22.6% in Africa and 6.0% in the USSR. Great differences were also observed between African countries, from 7.8% in Uganda to 45.1% in Congo. It is suggested that these variations are related to the existence of a “background” AFP level in healthy people, which may be different in various populations depending on genetic and nutritional factors. The differences may be a reflection of varying predisposition to cancer of the liver. Subordination de la speceficite du test serologique pour le depistage du cancer hepatique primitif dans diverses regions du monde a la sensibilite de la methode utilisee pour deceler l'alpha-fœtoproteine La valeur diagnostique de la methode de determination de l'AFP a ete etudite en fonction de la sensibilite de la technique utilisee pour deceler l'AFP. Les serums provenaient de cinq pays africains, de Singapour, de la Jamaique et de l'URSS; ils avaient deja ete controles au rnoyen du test standardise (technique de la precipitation en gelose) et ont ete reexamines par la methode d'immunoautoradiographie indirecte, qui est 30 a 50 fois plus sensible que le test standardise. Le pourcentage d'hepatomes reveles par l'irnrnunoautoradiographie est de ce fait passe de 75 a 89.2% pour les pays africains et de 64 a 87.1% pour l'URSS (parmi les cas confirmes histologiquement). La specificite diagnostique du test a considerablemmt diminue: un grand iiornbre de retactions positives a ete observe duns k groupe-teteenoin. La proportion de ces cas “faussement positifs” n'est pas egale dans les differentes parties du monde: 20.1% en Afrique et 6.0% en URSS. De grandes differences ont egalement ete observees entre les pays africains, ou le taux varie de 5% en Ouganda a 40.3% au Congo. On peut supposer que ces variations sont liees a l'existence d'un certain niveau “de base” de l'AFP chez les personnes en bonne sante, niveau qui peut ětre different selon les peuples, en fonction des facteurs genetiques et alimentaires. Ces variations peuvent correspondre a des differences de predisposition au cancer du foie.

Characteristics of tumors induced in mammals, especially rodents, by viruses of the avian leukosis sarcoma group.

Abstract: Publisher Summary This chapter analyzes the characteristics of avian leukosis sarcoma viruses (ALSV)-induced tumors in mammals, especially in rodents. ALSV, belonging to avian tumor viruses (ATV), represent a group of sarcoma and leukosis viruses capable of inducing various forms of predominantly malignant diseases in their natural hosts, chickens. Tumors can be induced by strains of ALSV with the help of heteroinduction. The first successful experiments on the induction of tumors and cystic hemorrhagic disease in rats were carried out in 1957 and 1958. It was shows that RSV was able to cause two types of pathological change in the same host: one, proliferative, leading to malignant tumors, and the other, lytic, represented by the development of cystichemorrhagic disease. There are four types of interaction between avian sarcoma viruses and mammalian tumor cells: virus-producing type, virogenic type, nonvirogenic type, and abortive type. Virus-producing type is found in mammalian tumors with the continuous production and release of infective virions. Virogenic tumor cells do not contain, do not produce, and consequently do not release infectious ALSV particles. A second characteristic property of virogenic mammalian tumor cells is that they can, under favorable conditions, transfer viral genetic material into susceptible avian cells, and as a result of this an avian cell is transformed into a malignant virus-producing or nonproducing cell. In case of nonvirogenic type of interactions, the isolation or production of infectious virus cannot be achieved by any known means currently. Abortive tumor cells can survive or multiply for various periods of time in the infected cells.

Evolution of complement-fixing antibody titers with the development of Burkitt's lymphoma.

Abstract: Sera of 29 patients with Burkitt's lymphoma (BL) were studied at different stages of the disease process for complement-fixing (CF) activities against a soluble antigen extracted from a leukaemia-derived and virus-producing lymphoblastoid line (QIMR-WIL line of Pope). The CF antibody activity was low (with a geometric mean titre (GMT) of 12.35) in sera from patients with controlled tumour, and high (GMT of 38) in patients with advanced or progressive tumours. Furthermore, in seven cases, the CF litres decreased with the regression of the tumour, and in five cases, the CF titres increased in parallel with the progression of the disease. This situation recalls that observed in acute viral infections, where CF antibodies disappear rapidly once the infection is controlled. CF and EA (early antigen (s)) antibodies should be studied in parallel on the same sera as a possible means for establishing prognosis in BL patients.

The aflatoxins and human liver cancer.

Abstract: The possible role of natural and synthetic chemical carcinogens in the aetiology of human liver cancer has been reviewed recently by Magee (1971). The synthetic chemical carcinogens generally have little relation to the situation in man and remain laboratory shelf carcinogens with the interesting exception of the nitrosamines. The possibilities among the natural carcinogens, however, appears more promising and the pyrrolidine alkaloids from Senecio and Crotalaria plants, the glycosides from the cycads, the toxic agents from rice contaminated by Penicillium islandicum, and the aflatoxins from the Aspergillus moulds have been the subject of much endeavour during the last decade.

Correlates of Histologic Differentiation of Carcinoma of the Penis

Abstract: Uganda, which is about 300 miles square and lies astride the equator, is a small country full of ecological and demographical contrasts. The altitude varies from two to nearly 17,000 feet, the climate changes from hot desert through temperate lacustrine areas to alpine pasture land, and there are more than 30 tribes in a population of only nine million people (Atlas of Uganda, 1967). It was no surprise, therefore, that cancer registration, started by the Department of Pathology of the Medical School as early as 1951, should delineate most peculiar patterns of tumour geography (Davies and Wilson, 1954). Mapping these patterns against amount of exposure in the environment has provided clues to the aetiology of many cancers. Examples include the association of Burkitt’s lymphoma with malaria (Kafuko and Burkitt, 1970) and of hepatocellular carcinoma with aflatoxin content of foodstuffs (Alpert, Hutt, Wogan and Davidson, 1971).

Etiology of Burkitt's lymphoma.

Abstract: The epidemiology of Burkitt’s lymphoma (BL) strongly favours the hypothesis of a vector transmitted factor playing a role in the development of the tumour (BURKITT, 1963). The serological association between a new herpes virus, discovered by Epstein et al. (1964), and this disease makes this virus an obvious canditate for etiology, although the ubiquitous presence of such an agent in all populations all around the world prevents from considering this virus as the only possible cause of the tumour.

Recent Techniques and Hypotheses in the Epidemiology of Liver Cancer

Abstract: Primary liver cancer, which can be so easily provoked in laboratory animals by a variety of chemical agents, is not a common disease in man, except in Africa. Although spontaneous primary hepatoma is rare in Western Europe and in the United States, it is commonly observed in Asia and Latin America and is exceedingly frequent in some parts of Africa.