ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Epidemiological evidence increasingly points to exogenous or endogenous oestrogens as a risk factor for breast cancer. However, it is unlikely that induction of oestrogen-dependent tumour growth is the sole contribution of oestrogens to tumour development in the mammary gland, because oestrogen receptors are barely detectable in normal mammary epithelial cells. In this review, I examine a mechanism for mammary carcinogenesis, which emphasizes tumour initiation by metabolic activation of oestrogens in combination with cell transformation and growth stimulation by oestrogen receptor-mediated processes. Catecholestrogen metabolites are capable of metabolic redox cycling between quinone and hydroquinone forms, a mechanism of free radical generation. Several types of direct and indirect free radical-mediated DNA damage are induced by oestrogens invitroand invivo, such as DNA single strand breaks, 8–hydroxylation of guanine bases, and DNA adduct formation by malondialdehyde, a decomposition product of free radical-induced lipid peroxides. The substrate for redox cycling and free radical generation may be 4–hydroxoestradiol, because this metabolite is formed from oestradiol by a specific oestrogen 4–hydroxylase detected in several human organs including mammary tissue. It has also been formed in organs of rodents where oestrogens induce tumours, with the exception of the liver. 4–Hydroxyoestradiol is a potent, long-acting oestrogen and may complete the carcinogenic process by stimulating receptor-mediated proliferation. An understanding of a possible mechanism of mammary carcinogenesis as a result of oestrogen-mediated initiation means that several prevention strategies, based on inhibiting metabolic activation of oestrogens or free radical action, can be developed.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study assessed whether there is any variation in the incidence of haematological malignancies between geographical areas of differing water supplies in the South West peninsula of the United Kingdom (1984 to 1988 inclusive). The possibility of correlations existing between variation in water quality and variation in the incidence of haematological malignancies was examined. Haematological incidence data, taken from the Leukaemia Research Fund's Data Collection Study, were mapped into 46 geographical areas of differing water supply. The distribution of the mapped cases was then tested for homogeneity using the Potthoff and Whittinghill (1966) test score. The age-adjusted incidence ratios calculated during the heterogeneity testing were examined for correlations with water quality indicators using correlation and stepwise regression. Significant heterogeneity in the incidence rates among water supply areas was observed for two groups of disease - acute leukaemias and myeloproliferative disorders. Three water quality indicators - pH, nitrate concentration and aluminium concentration - varied considerably over the study period. Significant correlations were observed between the standardized incidence ratios of five disease categories and some water quality indicators, especially aluminium and trihalomethane concentrations. The standardized incidence ratios of some haematological malignancies differed between geographical areas of water supply in South West England, and the evidence suggests that this variation may be associated with variation in water quality indicators. Although this lends support to similar findings in the United States of America, the pattern of correlations are affected by disease latency and statistical methodology.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

It has been suggested that the risk of stomach cancer is increased when there is a history of gastric ulcer, but decreased in those with a history of duodenal ulcer. To provide further information on the issue, data from a case–control study of gastric cancer conducted in greater Milan, northern Italy, between 1985 and 1993, were examined. There were 746 cases of gastric cancer below the age of 75 and 2,053 controls admitted to hospital for acute, non-neoplastic, non-hormone-related diseases. A total of 76 (10.2%) cases and 84 (4.1%) controls reported a history of gastric ulcer, corresponding to a multivariate odds ratio (OR) of 2.6 (95%) confidence interval, CI=1.8–.6). Fifty nine cases (7.9%) and 111 (5.4%) controls reported a history of duodenal ulcer, corresponding to an OR of 1.3 (95% CI=0.9–1.8). The OR of gastric cancer was significantly above unity for the first five years after diagnosis of gastric ulcer (OR =.4, 95% CI 3.7–4.8), and declined thereafter. No consistent pattern of risks was observed after duodenal ulcer. The present data therefore confirm that the risk of gastric cancer is increased after gastric ulcer. They do not support, however, a reduced risk after duodenal ulcer. This may be due to variable baseline characteristics of the populations studied, or to the different role and impact of Helicobacter pylori and other determinants of duodenal ulcer and gastric cancer in various countries.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The purpose of this study was to examine the change in incidence pattern of oesophageal cancer in the Cote-d'Or region (Burgundy, France). Data from the population-based cancer registry were used to study time trends between 1976 and 1993, according to sex, place of residence, subsite and histology. There was a non-significant increase in incidence of oesophageal cancer, by an average of + 1.0% [confidence interval:- 0.7; + 2.8] per year in men and + 2.0% [CI: - 3.0; + 6.9] in women. In men, variations in incidence were minor according to subsite and place of residence, among the six age groups studied. In contrast, there were important changes among histological types. Rates of squamous cell carcinoma remained stable, but those of adenocarcinoma increased significantly (P < 0.001). They represented 5.6% of known histological types, between 1976 and 1987, and 20.1% in 1991-3. Similar trends were observed in women. This rising incidence of adenocarcinomas, observed later than in the UK or the USA, started in 1987-90 and was particularly pronounced between 1991 and 1993. In view of this sharp increase in incidence of oesophageal adenocarcinomas, research on their aetiological determinants is urgently needed.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Migration has been related to the utilization of preventive care services. We analysed the relation between cervical cancer screening and migration within the same country and socioeconomic status in a context in which there is no organized screening. The health survey of Barcelona (Spain) was the data source. Barcelona, a city in north eastern Spain, has experienced important migration from the south and other regions of Spain. Variables studied were the migrant women's year of arrival, age at arrival, educational attainment and Pap smear test uptake. Multivariate logistic regression analysis was performed to examine the correlations among the variables of interest. Just over 30% of the women had never had a Pap smear test. Uptake was higher among younger, educated women born either in Barcelona or abroad. After adjusting for age, migrant women were at higher risk for not participating in screening tests (odds ratio: 1.23; 1.09-1.39); but after adjusting for educational attainment and age, the odds ratio was no longer significant. This study shows that migrants within Spain have less access to preventive services, such as cervical cancer screening in an opportunistic setting. However, this association is almost completely explained by socioeconomic status. Migration could be seen as a social factor that puts people at risk of falling into lower socioeconomic status associated with poor access to screenin

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

During a prospective screening study for recto-sigmoid adenomatous polyps, the influence of the following risk factors was evaluated: age; gender; body mass index; heredity for colorectal malignancy; diabetes; hypertension; constipation; previous gastric surgery; previous gastric add inhibition; alcohol and cigarette consumption; serum cholesterol; serum triglycerides; and serum gastrin. Screening fibre-sigmoidoscopy of 665 patients (aged between 50 and 60 years) at a clinical rehabilitation centre for gastrointestinal and metabolic diseases showed that 146 had one or several adenomas. The study population was overweight by a mean of about 15%. Comparison of those with and those without adenoma using univariate analysis, showed that the group with adenomas had higher serum triglyceride values, drank more alcohol on a regular or excessive basis, were more frequent smokers, and had a tendency to raised fasting serum glucose. In a multivariate analysis, age, high serum triglycerides and high alcohol consumption were risk factors for recto-sigmoid adenomas. The risk factor profile identified in this study may help in the selection of individuals for screening sigmoidoscopy from a similar background population. It also identifies target conditions for primary prevention of colorectal neoplasia.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study aimed to identify the social, cultural and psychological characteristics influencing behaviour in a cancer mass screening campaign in a French population. The intention to take a screening test and actually doing it was studied, in particular. A self reported-questionnaire was mailed in December 1992 to a random sample of people living in Caen (western France), and aged from 45-74 years. The sample was formed by random selection from electoral registers. The study was population based, in the Caen area, department of Calvados, France. The questionnaire comprised 26 open and closed questions. Starting in February 1993, the occult blood screening test (haemoccult IIR) for colorectal cancer was offered by general practitioners (GPs), occupational health doctors and pharmacists in the Caen area to all those aged 45-74 years. From 1 February 1993 to 30 June 1994, the data on the mass screening campaign were centralized and the study population divided into those who took the screening test and those who did not. Of the 1,129 persons contacted, 645 (57.1%) returned the questionnaire. After exclusions, 585 questionnaires were used for analysis. The results show that whether a person will actually take a screening test cannot be predicted from their intention to do so. The sociodemographic and cultural characteristics influencing the intention to take the test differ from those influencing execution of the test. Among the variables tested here, the following four sociodemographic and cultural characteristics were independently predictive of actually taking the screening test for colorectal cancer: compliance with the health insurer's advice; low or medium sociodemographic status, living with a partner (or widowhood); and not knowing someone with cancer. The analysis of the quantitative and qualitative differences between the intention to take the test and actually doing it could elucidate the reasons underlying refusal. Poor screening compliance has multiple causes. A record of intention to take a screening test alone is not appropriate. This type of study should no longer be carried out to determine the mechanisms underlying behaviour towards secondary prevention.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The aberrant crypt foci assay has been used extensively to study different compounds for chemopreventive action, but almost all investigations have used initiators not normally found in the diet. In the present study two food-bome initiators, 2-amino-3-methyl-imidazo[4,5-f|quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[ 4,5-b]pyridine (PhIP) were used. To simulate the human exposure further, we chose a feeding regimen with continuous low IQ- and PhlP-doses. Throughout the study female mice were given diets with or without 0.03% IQ or 0.03% PhIP. Two additional groups were given azoxymethane (AOM) (5 mg/kg body weight) and 1,2-dimethylhydrazine dihydrochloride (DMH-2HCI) (20 mg/kg body weight), respectively, one dose a week for two weeks. Animals were killed after four and 10 weeks. After four weeks only the mice dosed with IQ and PhIP had aberrant crypt foci. A much higher number of aberrant crypt foci were found in the IQ mice (31.8 ± 5.2) than in the PhIP mice (0.5 ± 0.3). After 10 weeks aberrant crypt foci were found in all dosed groups. The IQ mice had significantly more (P ≤0.001) small and total aberrant crypt foci than the other groups. AOM and DMH induced a higher percentage of medium or large sized aberrant crypt foci than PhIP or IQ. The interpretation of the aberrant crypt foci as precursor lesions for colon cancer in the PhIP and IQ mice is difficult because PhIP and IQ have not been reported to be colonic carcinogens. If cooked food mutagens such as IQ or PhIP are to be used as initiators in the aberrant crypt foci test, the use of rats may be preferable.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The trace element vanadium was investigated for its anti-neoplastic role in relation to haematological status, hepatic histopathology and histochemical analysis of glycogen in liver. Its impact on the survival of male Sprague-Dawley rats subjected to a two-stage hepatocarcinogenesis regimen was also assessed. Initiation was performed using a single intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg) followed by promotion with phenobarbital (0.05%) in a basal diet. Vanadium supplementation as ammonium monovanadate at 0.5 ppm vanadium in drinking water was given ad libitum throughout the experiment (20 weeks), before the initiation (4 weeks), or during the promotional period (14 weeks). At the end of the study, there was a significant decrease in red blood cell count, haemoglobin content, haematocrit value, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, plasma volume change and total white cell count, with a concurrent alteration in lymphoid:myeloid ratio in DENA control animals compared with their normal counterparts. Vanadium supplementation throughout the study or before the initiation significantly reversed the DENA-induced alterations in most of the haematological indices. A single intraperitoneal injection of DENA also depleted the plasma albumin concentration, raised the plasma globulin content, and decreased the ratio of albumin to globulin. These altered features began to return to normal following vanadium supplementation. Supplementary vanadium also elicited substantial protection against DENA-mediated rat liver carcinogenesis. This was fairly evident from hepatic histology and evaluation of glycogen accumulation by periodic acid-Schiff reaction. The survival of DENA-treated animals was considerably increased in the presence of vanadium. The critical involvement of vanadium in modulating several factors associated with erythropoiesis under carcinogenic challenge may thus have a possible impact on the eventual increased survival of the host.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID