ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Energy balance results from the exact equilibrium between caloric intake and caloric expenditure. A caloric intake larger than caloric expenditure results in overweight, even obesity, but other determinants, like hormonal dysfunction and/or genetic traits may play a part in obesity syndrome. Obesity, and even overweight, have been recognized as risk factors for the development of cancers. Human epidemiological studies, which have tended to establish the nature of the relationship between energy balance and cancer, are summarized first, with the influence of the various factors which act both on obesity and on cancer risk. Among these factors are the macronutrients responsible for the caloric intake, and some lifestyle factors (physical activity, drinking habits and tobacco use). Second, the animal studies help to distinguish between different relevant factors, and to understand some of the underlying mechanisms. However, the insulin-resistance syndrome, which appears to underlie the relationship between obesity and hormone-dependent cancers, and possibly colon cancer, is only relevant to human physiology because hormonal alterations are part of it. Prevention of hyperinsulinemia, insulin resistance and the accompanying visceral obesity appears to be a major public health task for the prevention of cancers.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

This paper (and an extensive supplementary report) considers how far cancer/risk factor associations based on epidemiology have been confirmed by evidence from 226 studies involving interventions other than smoking. Many are small, uncontrolled, of unrepresentative populations, concern cancer markers not cancer, and may involve combinations of agents. Many agents suspected of causing cancer are untested by intervention trials. For seven of 16 agents tested (fibre, folic acid, low-fat diet, riboflavin, zinc, vitamin Bs, and vitamin D), the evidence is clearly inadequate to confirm or deny the epidemiology, while the evidence relating to calcium only concerns biomarkers. For other agents, the evidence relating to cancer itself is weak. In studies where cancer is the endpoint, only three effects have been replicated: (a) selenium supplementation and decreased liver cancer incidence, (b) treatment by the retinoid etretinate and reduced bladder tumours in susceptible individuals, and (c) β-carotene supplementation and increased lung cancer incidence. Studies involving pre-cancerous conditions as the endpoint, which have a number of practical advantages, more frequently report benefits of intervention. Thus, oral pre-cancerous lesions can certainly be reduced by β-carotene, vitamin A, and other retinoids, and possibly by vitamin E. It also seems that retinoids can reduce pre-cancerous cervix, skin and lung lesions, that vitamin C and the NSAID sulindac can reduce colonic polyps, and that sunscreens can reduce solar keratoses. Our findings clearly show that the great majority of causal relationships suggested by epidemiology have not been validated by intervention trials. This may be partly due to lack of suitable studies of adequate size or duration, or to using single dietary compounds as agents that are by themselves not responsible for the epidemiologically-observed associations between diet and cancer. However, this lack of validation must cause concern in view of the markedly conflicting evidence on β-carotene and lung cancer between epidemiological and intervention studies. More intervention studies are needed, but in their absence, caution in interpreting epidemiological findings is warranted.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

It has been suggested that components of our diet play an essential role in carcinogenesis. Anthropometric indices, such as body weight and height, have often been considered as measurements of prevailing diet and nutrition in childhood respectively. To investigate to what extent height and body weight are associated with the risk of gastrointestinal cancer, data from a Norwegian screening programme for tuberculosis were analysed. More than 1,100,000 individuals, aged 30–69 years at the time of examination, were included in the study. Body weight, expressed as Quetelet's index (QI), and height records were linked with vital status data from Statistics Norway and the Cancer Registry of Norway. The analysis shows that individuals in the first quintile of height had a lower relative risk than later quintiles for colon cancer, independent of sex and stage of disease at completion of follow-up. The association between height and rectal cancer is similar, but weaker. Men in the fifth quintile of QI have a relative risk of 1.39 for colon cancer, compared with the first quintile, and they also have a slightly elevated risk for rectal cancer. Among women, the pattern is unclear, but we observed a significant relationship between high QI and cancer of the gallbladder. Our results indicate that prevailing diet and living conditions in early life do play a role, and seem to support the hypothesis that anthropometric indices could be of importance as indirect markers for the risk of colon cancer and, to some extent, for cancer of the rectum and gallbladder.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Epidemiological studies have suggested that socioeconomic conditions, including dietary factors, can affect the risk of several gastric cancers. Anthropometric indices, such as body weight and adult height, have been considered as measurements of prevailing diet and nutrition, respectively, in early life. The objective of this study was to evaluate the association between body mass and height and the risk of cancer of the oesophagus and stomach. The analysis was based on data from a national Norwegian screening programme for tuberculosis, which ran from 1963 to 1975, screening more than 1,100,000 individuals, aged 30–69 years at the time of examination. The participants were followed until December 1989. Body weight (expressed as Quetelet's index (QI)) and height records were linked with vital status data from Statistics Norway and the Cancer Registry of Norway. Individuals in the first quintile of height appear to have an increased risk of oesophageal cancer in both sexes. Low QI was found to increase the risk for oesophageal squamous cell carcinoma, whereas high QI was linked to an elevated risk of oesophageal adenocarcinoma. The analysis reveals a relationship between low QI and the risk of stomach cancer. There were no associations between stomach cancer and height. These associations indicate that prevailing and early life conditions could play a role in later cancer development; they support the hypothesis that anthropometric indices are important as markers for the risk of oesophageal cancer and, to some extent, for cancer of the stomach.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Use of hormone replacement therapy (HRT) has been associated with increased risk of breast cancer, and it is possible that this reflects a positive association between HRT use and risk of proliferative forms of benign breast disease (BBD), conditions which are thought to have pre-malignant potential. The purpose of the present investigation was to study the association between HRT use and risk of benign proliferative epithelial disorders of the breast (BPED). The study was undertaken using the 56,837 women within the Canadian National Breast Screening Study (NBSS) who completed self-administered lifestyle and dietary questionnaires. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40–59 at recruitment.) During the course of the follow-up period, a total of 691 women in the dietary cohort were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a sub-cohort consisting of a random sample of 5681 women (including 65 of the subjects with BPED) was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 691 cases and 5443 non-cases. In post-menopausal women, in whom most of the reported use occurred, there was a positive association between duration of HRT use and risk of BPED, the adjusted incidence rate ratio (95% confidence interval) in those who had used HRT for more than 8 years being 1.70 (1.06–2.72). There were too few cases of atypical BPED for meaningful analysis, but results for those whose BPED showed no atypia were similar to the overall results. Further analyses conducted separately in the screened and control arms of the NBSS were similar to those observed overall, as were those conducted separately for screen-detected and interval-detected BPED.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Interval cancers represent the major limitation of screening for colorectal cancer with the faecal occult blood test. The aim of this study was to describe the characteristics of interval cancers and the sensitivity of the screening programme in a well-defined French population. During five screening rounds, 398 cancers were diagnosed in those of the population having performed at least one screening test; 57.8% of them were interval cancers. The proportion of interval cancers was higher among cancers of the rectal ampulla (72.2%) than among cancers of other sites (52.9%) (P< 0.001). The proportion of TNM stage I and II were higher among screen-detected cancers (73.8%) than among interval cancers (57.4%). The overall sensitivity of the screening programme was 62.9% within 1 year, and 48.7% within 2 years. An improvement in the sensitivity of the faecal occult blood test for colorectal cancer screening is needed, without an unacceptable loss of specificity.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

In order to assess links between renal cell cancer (RCCs) and transitional cell cancers (TCCs) of the kidney and cancer development in other organs of the abdominal cavity, incidence data from theCancer Incidence in Five Continents (Vol VII)were compared between various cancer registries in Europe. Significant correlations which persisted on partial analysis were observed between RCCs and carcinomas of the colon and gallbladder, as well as between the latter themselves. Kidney TCCs, in contrast, were associated with tumours of the urinary bladder. In addition, significant correlations between hepatocellular, but not cholangiocellular carcinomas, and gallbladder and colon cancers were observed. Data for pancreas and gallbladder neoplasms also correlated. Prostate cancer incidences, while positively linked to RCCs, negatively correlated with gallbladder rates. The results point to shared risk factors for RCCs and adenocarcinomas in a number of organs, suggesting a role for humoral agents. The present findings also underline the necessity of distinguishing between tumour types within organs in epidemiological investigations of causal influences.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Using data of a case-control study conducted in Italy between 1992 and 1996 on 1225 cases of colon cancer and 4154 controls, we have evaluated the effect of selected established risk factors in subjects with, and in those without, familial propensity (134 cases, 146 controls); there were non-significant associations between education and meal frequency and colon cancer risk. Physical activity, high energy and low vegetable intake were significantly related to colon cancer risk in subjects without familial predisposition, but showed no relationship in those with family history of colorectal cancer: the ORs were 1.1 for the lowest level of physical activity, 0.7 for the highest tertile of energy intake, and 1.0 for the lowest one of vegetable intake. These findings would suggest that genetic predisposition can make the influence of environmental factors for defining the risk of colon cancer weak and/or difficult to estimate.

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0959-8278    

出版商:OVID    

年代:1999

数据来源: OVID