Showing papers by "International Agency for Research on Cancer published in 1971"

Time trends of intestinal and diffuse types of gastric cancer in the United States.

Abstract: All histologically confirmed gastric cancer cases diagnosed during the periods 1940–1944 and 1960–1964 at the Hartford Hospital were classified into three groups: intestinal, difuse and others, according to a modified Lauren's classification. A reduction in the frequency of intestinal type carcinoma was observed between the earlier and the later time periods. Although this decrease was not statistically significant, it persisted within each sex. The cases were also subdivided into high- and low-risk groups according to the risk for gastric cancer prevailing at their place of birth. As expected, the intestinal type carcinoma was the most predominant in the high-risk group. This predominance persisted within each sex and time period category and it was more noticeable among female than among male cases. These findings support the hypothesis that these two types of gastric cancer, intestinal and difluse, differ not only structuraily and epidemiologically, but also etiologically.

Nasopharyngeal carcinoma in non-Chinese populations with special reference to south-east Asia and Africa.

Abstract: Nasopharyngeal cancer (NPC) is very common in Chinese, the incidence rates (age-adjusted to the “world” population distribution) per 100,000 per annum varying between 10 to 20 for males and 5 to 10 for females. In virtually all occidental countries, the rates are very low, generally well below 1.0 per 100,000 per annum. The evidence suggesting intermediate levels of risk in certain non-Chinese mongoloid populations in South-East Asia, in the Sudan and the Maghreb, is examined. Although whenever possible incidence rates are quoted, most of the available data are based on relative frequency series, often with rather small numbers. Rare in Japan and India, NPC is fairly common in non-Chinese mongoloid groups in South-East Asia. NPC incidence in Tunisia is raised, and the relative frequency is probably raised in the Sudan and Algeria. NPC is probably not unduly common in Kenya or Uganda but there are differences between ethnic groups in these countries which may be related to environmental factors. NPC incidence in Hawaii is raised for all ethnic groups, the rate for male Hawaiians (7.8) approaching that for male Chinese (10.4). In Israel, the incidence in the non-Jewish (Arab) population and in Jews born in Africa or Asia (many of whom were born in Morocco or Tunisia) is higher than in Israel-born Jews or in Jews born in America or Europe. The effect of intermarriage with Chinese is examined. There is a general trend suggesting that NPC is commoner in those South-East Asian groups with admixture of Chinese blood, exemplified by NPC incidence in Singapore where the rates for male and female Chinese were 20.2 and 9.0 whereas those for the mongoloid Malays were 5.8 and 2.0 respectively. By contrast, the rates for the caucasoid Indians and Pakistanis were 0.2 and 0. It is highly unlikely that these differences are artefactual. The demonstration of an intermediate NPC risk level in Tunisia and other parts of Africa should, when confirmed, permit examination of viral and other aetiological hypotheses in populations with little or no Chinese genetic material. Le cancer du rhinopharynx se rencontre tres frequemment chez les Chinois. Les taux d'incidence (ajustes a la structure d'ǎge de la population “mondiale”) pour 100 000 habitants et par an, varient en effet entre 10 et 20 chez les hommes et 5 a 10 chez les femmes. Dans la quasi totalite des pays occidentaux, les taux correspondants sont tres faibles, se situant en general bien au-dessous de 1.0 pour 100 000 habitants et par an. On etudie actuellement des indices laissant supposer l'existence de niveaux de risque intermediaires dans certaines populations mongoloides non chinoises de l'Asie du Sud-Est, au Soudan et dans le Maghreb. Bien que des taux d'incidence soient indiques chaque fois que possible, la plupart des donnees disponibles ont ete tirees de series de frequences relatives, souvent fondees sur des chiffres plutǒt faibles. Rare au Japan et en Inde, le cancer du rhinopharynx est assez contmun dans les groupes mongoloides non chinois du Sud-Est de l'Asie. L'incidence de ce cancer est elevee en Tunisie, et il est vraisemblable qu'il en est de měme de sa frequence relative au Soudan et en Algerie. Il n'est probablement pas indǔment frequent au Kenya et en Ouganda, mais on observe dans ces pays, entre groupes ethniques, des differences qui peuvent ětre liees a des facteurs de milieu. A Hawaii, l'incidence du cancer du rhinopharynx est elevee pour tous les groupes ethniques, le taux chez les Hawaiiens (hommes) (7.8) approchant de celui des Chinois (hommes) qui est 10.4. En Israel, l'incidence de ce cancer dans la population non juive (arabe), ainsi que chez les Juifs nes en Asie ou en Afrique (au Maroc ou en Tunisie pour nombre d'entre eux), est plus elevee que chez les Juifs nes en Israel ou chez ceux qui sont nes tn Amerique ou en Europe. L'influence possible de manages avec des Chinois est actuellement etudiee. On observe en effet une tendance generate suggerant que le cancer du rhinopharynx est plus commun dans les groupes de population de l'Asie du Sud-Est melanges de sang Chinois, tendance qui est mise en relief par l'incidence de ce cancer a Singapour, ou les taux pour les chinois de sexe masculin et de sexe feminin sont respectivementde 20.2 et de 9.0, tandis que les chiffres correspondants pour les Malais (mongoloids) sont respectivement de 5.8 et de 2.0. Faisant contraste avec ces chiffres, les taux chez les Indiens et Pakistanais (caucasoides) sont respectivement de 0.2 et de 0. Il est hautement improbable que ces differences soient des phenomenes artificiels ou accidentels. L'existence d'un niveau de risque intermediaire en Tunisie et dans d'autres parties du monde, si elle est confirmee, devrait permettre d'etudier dans des populations n'ayant pas ou seulement tres peu de materiel genetique chinois, les hypotheses virales ainsi que d'autres hypotheses etiologiques.

An epidemiological analysis of cancer vaccines.

Abstract: The logistic and epidemiological problems associated with the development of an effective virus vaccine for cancer are discussed. It is shown that if human tumours are caused by viruses with short latent periods, it will be possible to test the effectiveness and safety of the vaccine without following up unrealistically large control and experimental groups. On the other hand, if the viruses concerned are non-specific, and only a small proportion of the infected population develops cancer after a long and varied latent period, it will be very difficult to test the effectiveness of such vaccines in present society. This is due to the large number of individuals who would have to be followed up for prolonged periods. Analyse Epidemiologique des Vaccins Anticancereux Les problemes logistiques et epidemiologiques que pose la mise au point d'un vaccin viral efficace contre le cancer sont examines dans le present document. Il y est montre que si les tumeurs humaines sont dues a des virus dont la periode de latence est de breve duree, on pourra verifier l'efficacite et l'innocuite du vaccin sans devoir “suivre” des groupes temoins et experimentaux par trop importants. Mais si les virus en cause ne sont pas specifiques et si seule une faible proportion de la population infectee est atteinte de cancer apres une periode de latence longue et diverse, il sera tres difficile de verifier l'efficacite de ces vaccins dans les societes actuelles, en raison du grand nombre de personnes qui devraient faire l'objet d'une observation de longue duree.

Storage levels of DDT metabolites in mouse tissues following long term exposure to technical DDT.

Abstract: The storage levels of DDT and its metabolites, following the long term administration of technical DDT at the dose levels of 2, 20, 50 and 250 ppm to mice, were evaluated in the fat tissue, liver, kidney, brain and reproductive organs. In addition, storage levels were evaluated in foetuses and newborns of DDT-treated mothers. Apart from op'-DDT, there was a direct relationship between the concentration of each metabolite in each organ and the dose to which the animal was exposed. The highest concentration of DDT and metabolites was found in the fat tissue followed by reproductive organs, liver and kidney together, and lastly brain. The most prevalent metabolite was pp'-DDT, except in the liver, where pp'-DDD showed the highest concentration. Pregnant females had lower concentrations of all metabolites than non-pregnant females. The concentration of residues in samples of total foetal litters was directly related to the concentration of DDT fed to the mother. There was a strong negative correlation between the concentration of pp'-DDT and that of pp'-DDD in the foetuses and the placentas of the same litter. A significant increase in whole body DDT concentration was observed shortly after birth.

Recherche de particules virales dans des lignées cellulaires de hamster transformées par le virus de rous investigations on the presence of viral particles in rous transformed hamster cell lines

Abstract: In the framework of a study on the recovery of the Rous Sarcoma Virus (RSV) from transformed mammalian cells, nine Syrian hamster cell-lines transformed by RSV were examined by electron microscopy. Six of these lines were obtained from BHK 21/Clone 13 cells transformed in vitro by RSV, either Schmidt-Ruppin strain (SR-RSV) or Bryan strain (B-RSV), one of them being supertransformed by polyoma virus. Another line (RSH) was obtained from embryonic hamster cells transformed in vitro by SR-RSV. Two lines resulted from in vivo experiments: SR/Cl2 was obtained from a SR-RSV-induced tumour in a Syrian hamster; and RS2-TH2 represented an in vitro cultured tumour obtained in a Syrian hamster by the inoculation of RS2 cells transformed in vitro by SR-RSV. All these lines had the group-specific antigen (GS) and it was possible to rescue RSV from all lines except SR/Cl2 when they were cultivated in association with permissive chick cells. No C-type virus particles could be observed either in the six lines transformed in vitro or in two lines (RSH and SR/Cl2) transformed in vitro. On the contrary, the line RS2-TH2 contained C-type particles, morphologically similar to murine leukemia virus, and probably representing a latent hamster virus. In line SR/Cl2, A-type particles were found associated with mitochondria. The significance of the presence of these particles in this only non-virogenic line is discussed. Finally, in all the hamster lines examined, R-type particles were observed. They were more numerous in the in vivo transformed lines than in the in vitro transformed lines. Resume Duns le cadre d'une ttude de la rkcuptrution du virus de Rous (RSV) a partir de cellules de mummifbres trunsforme'es, neuf ligntes cellulaires de hamster syrientransformies par le virus de Rous ont ttexuminees au microscope tlectronique. Sixde ces ligntes ttaient issues de la transformation de cellules BHK Zl/clone 13 par RSV, souche Schmidt-Ruppin (SR-RSV) ou souche Bryan (B-RSV). Une de ces six ligntes avait Cte'surtrunsformte par le virus polyome. Une uutre IignCe (RSH) provenuit de la transformation de cellules enibryonnaires de hamster syrien par SR-RSV. Les deux dernibres (SRICI, et RS,-TH,) provenaient de turneurs de hamster syrien, induites I'une (SRICI,) par SR-RSV, la seconde (RS,-TH,) par la grefe invivo d'une lignte trunsformee in vitro par SR-RSV. Toutes ces Iigntes posstdaient I'untigbne spCciJique de groupe (GS) et toutes, sauf la lignte SRICI „permettaient la rtcupkration du RSV qiiand elles Ctaient cultivCes en association avec les cellules permissives de poule. Dans les sept Iignees transformees in vitro, aucune purticule de type C n'a puitre observte. A I'oppo, la lignte RS,-TH, produisait des particules virales de typeC. Il semble qu'elles representent un virus latent du hamster dont la production n'est pas specifique de la transformation par RSV. De plus, dans la lignee SR/Cl2, des particules associees aux mitochondries de type A ont ete observees. La signification de leur presence en relation avec la non-virogenie de cette lignee est discutee. Enfin, dans toutes ces lignees de hamster se trouvaient des particules de type R, plus nombreuses dans les deux lignees transformees in vivo et dans la lignee RSH que dans les lignees transformees in vitro, issues des cellules BHK 21.

Effect of perinatal administration of 7,12-dimethylbenz(a)anthracene on the later response to a subcutaneous teflon implant.

Abstract: The possible effect of the exposure of mice during the perinatal period to minute doses of 7,12-dimethylbenz(a)anthracene (DMBA) on the response to a subcutaneous implantation later in life of a teflon disc was investigated. The present results indicate that the prenatal or neonatal exposure to DMBA had no effect on the incidence of tumors occurring around the teflon implant nor on the average age at death of mice bearing tumors at the site of the teflon implant. The incidence of tumors occurring at various sites was higher in the descendants of females given 400 μg DMBA during the late period of pregnancy than in offspring of untreated mothers which were given 0.1 μg DMBA at birth.