Four authoritative reviews of active smoking and breast cancer have been published since 2000, but only one considered data after 2002 and conclusions varied. Three reviews of secondhand smoke (SHS) and breast cancer (2004-2006) each came to different conclusions. With 30 new studies since 2002, further review was deemed desirable. An Expert Panel was convened by four Canadian agencies, the Ontario Tobacco Research Unit, the Public Health Agency of Canada, Physicians for a Smoke-Free Canada and the Canadian Partnership Against Cancer to comprehensively examine the weight of evidence from epidemiological and toxicological studies and understanding of biological mechanisms regarding the relationship between tobacco smoke and breast cancer. This article summarises the panel's full report (http://www.otru.org/pdf/special/expert_panel_tobacco_breast_cancer.pdf). There are 20 known or suspected mammary carcinogens in tobacco smoke, and recognised biological mechanisms that explain how exposure to these carcinogens could lead to breast cancer. Results from the nine cohort studies reporting exposure metrics more detailed than ever/never and ex/current smoker show that early age of smoking commencement, higher pack-years and longer duration of smoking increase breast cancer risk 15% to 40%. Three meta-analyses report 35% to 50% increases in breast cancer risk for long-term smokers with N-acetyltransferase 2 gene (NAT2) slow acetylation genotypes. The active smoking evidence bolsters support for three meta-analyses that each reported about a 65% increase in premenopausal breast cancer risk among never smokers exposed to SHS. The Panel concluded that: 1) the association between active smoking and breast cancer is consistent with causality and 2) the association between SHS and breast cancer among younger, primarily premenopausal women who have never smoked is consistent with causality.
The effect of age on the number and morphology of optic nerve axons in adult Brown Norway rats (5-31 months old) (n=29) was examined using transmission electron microscopy (TEM). By manually counting every axon in areas representing 60% of the optic nerve cross-section, we found a significant negative correlation between age and axon count (R(2)=0.18, P
Alcohol, tobacco and coffee consumption and the risk of pancreatic cancer: results from the Canadian Enhanced Surveillance System case-control project. Canadian Cancer Registries Epidemiology Research Group.
The relationship between alcohol, tobacco and coffee consumption and pancreatic cancer was investigated using population-based case-control data obtained from eight Canadian provinces. Our findings are based on analyses performed on 583 histologically confirmed pancreatic cancer cases and 4813 controls. Questionnaire data were obtained directly from 76% of the cases. Male subjects with 35 or more cigarette pack-years had an increased risk of developing pancreatic cancer relative to never smokers (OR= 1.46, 95% CI 1.00-2.14). Similarly, women reporting at least 23 cigarette pack-years of smoking had an odds ratio of 1.84 (95% CI 1.25-2.69). For the most part, consumption of total alcohol, wine, liquor and beer was not associated with pancreatic cancer. Coffee drinking was not related to pancreatic cancer. More work is needed to clarify the role of these and other potentially modifiable risk factors as a means to reduce the incidence of this disease for which treatment results remain disappointing.
There is some evidence to suggest that workers in animal-related occupations are at increased risk of developing lymphohematopoietic cancers. This study aimed to examine the risk of leukemia, non-Hodgkin's lymphoma (NHL), and multiple myeloma associated with occupational exposure to animals.
We used data from a multi-site, population-based case-control study using mailed questionnaires which had taken place in eight of ten Canadian provinces, during 1994-1998. There were 1023 leukemia cases, 1577 NHL cases, and 324 multiple myeloma cases (all histologically confirmed) and 4688 population-based controls. Animal-related occupations were identified from a lifetime occupational history. Subjects in animal-related jobs were compared with others using logistic regression for the risk of leukemia, NHL, and multiple myeloma.
Compared to subjects without occupational exposure to animals, occupational exposure to beef cattle increased the risks of leukemia (odds ratio (OR) 2.0, 95% confidence interval (CI) 1.2-3.3) and NHL (OR 1.8, 95% CI 1.1-2.9). No other animal exposure was consistently associated with risk of lymphohematopoietic cancer. An unexpected protective association was observed between work as a fisherman and leukemia (OR 0.4, 95% CI 0.2-0.8) and NHL (OR 0.6, 95% CI 0.4-0.9).
This population-based case-control study found that those individuals working in occupations associated with beef cattle are at increased risk for developing leukemia and lymphoma while those working in occupations requiring the handling of fish are at decreased risk of leukemia and lymphoma.
Epidemiological studies suggest that fish consumption may be a protective factor against the development of prostate cancer. We investigated the association between prostate cancer risk and fresh and preserved fish consumption among participants of a population-based case-control study (1,534 cases, 1,607 controls). Fish intake was measured using a dietary questionnaire that collected both frequency of consumption of a given portion size. Logistic regression analysis demonstrated an inverse association between preserved fish and prostate cancer risk for all levels of consumption, but reductions only reached statistical significance for the category of 1 to 3 servings of preserved fish per month (odds ratio = 0.78, confidence interval = 0.64-0.95). Consumption of any fat or energy from preserved fish was also associated with reduced risk. There was no suggestion of reduced prostate cancer risk with consumption of fresh and canned fish. Our results suggest that consumption of preserved fish may reduce the risk of developing prostate cancer.
To investigate the association of alcohol use and night driving with traumatic snowmobile fatalities.
Traumatic deaths occurring while driving a snowmobile during the years 1985 to 1990 were reviewed. A sample of 1989 to 1990 fatal motor vehicle driver and motorcycle driver accidents were used as controls. Records were obtained from the provincial coroner.
One hundred eight snowmobile fatalities, 432 motor vehicle fatalities, and 108 motorcycle fatalities were included. Young men (mean age, 30 years) made up the snowmobile fatalities population, with weekend fatalities predominating (67%). Snowmobile fatalities were associated with use during times of suboptimal lighting (crude odds ratio, 1.9 [95% confidence interval, 1.1-3.3]; P
Comment In: Ann Emerg Med. 1995 May;25(5):717-87741357
The authors conducted a population-based, case-control study of 21,022 incident cases of 19 types of cancer and 5,039 controls aged 20-76 years during 1994-1997 to examine the association between obesity and the risks of various cancers. Compared with people with a body mass index of less than 25 kg/m(2), obese (body mass index of > or = 30 kg/m(2)) men and women had an increased risk of overall cancer (multivariable adjusted odds ratio = 1.34, 95% confidence interval (CI): 1.22, 1.48), non-Hodgkin's lymphoma (odds ratio = 1.46, 95% CI: 1.24, 1.72), leukemia (odds ratio = 1.61, 95% CI: 1.32, 1.96), multiple myeloma (odds ratio = 2.06, 95% CI: 1.46, 2.89), and cancers of the kidney (odds ratio = 2.74, 95% CI: 2.30, 3.25), colon (odds ratio = 1.93, 95% CI: 1.61, 2.31), rectum (odds ratio = 1.65, 95% CI: 1.36, 2.00), pancreas (odds ratio = 1.51, 95% CI: 1.19, 1.92), breast (in postmenopausal women) (odds ratio = 1.66, 95% CI: 1.33, 2.06), ovary (odds ratio = 1.95, 95% CI: 1.44, 2.64), and prostate (odds ratio = 1.27, 95% CI: 1.09, 1.47). Overall, excess body mass accounted for 7.7% of all cancers in Canada-9.7% in men and 5.9% in women. This study provides further evidence that obesity increases the risk of overall cancer, non-Hodgkin's lymphoma, leukemia, multiple myeloma, and cancers of the kidney, colon, rectum, breast (in postmenopausal women), pancreas, ovary, and prostate.
The relationship between occupational exposure to magnetic fields and brain cancer in men was investigated using population-based case-control data collected in eight Canadian provinces. Emphasis was placed on examining the variations in risk across different histological types.
A list of occupations was compiled for 543 cases and 543 controls that were individually matched by age. Occupations were categorized according to their average magnetic field exposure through blinded expert review ( or = 0.6 microT). In total, 133 cases (14%) and 123 controls (12%) were estimated to have at least one occupation whereby magnetic field exposures exceeded 0.3 microT. Odds ratios (OR) were generated using conditional logistic regression, and were adjusted for suspected occupational risk factors for brain cancer.
A non-significantly increased risk of brain cancer was observed among men who had ever held a job with an average magnetic field exposure >0.6 microT relative to those with exposures
Several population-based health databases exist in Canada which provide valuable systematic information for facilitating epidemiological evaluation of human health in the Great Lakes Basin. They include the long-established Canadian Mortality Database, a national birth defects registry, a provincial hospitalization database, and provincial and national cancer registry systems. The most recent addition is the National Enhanced Cancer Surveillance System which currently is being implemented to allow for detailed evaluation of air and water quality concerns in relation to a range of cancer types. The system includes statistical evaluation of geographical cancer incidence patterns; development of a national environmental quality database; and systematic collection of individual risk factor information for a large number of newly diagnosed cancer cases and a population control group. A brief description of each database and examples of relevant research using each of these databases is presented.
Epidemiologic studies have suggested that some dietary factors may play a role in the etiology of ovarian cancer, but the findings have been inconsistent. We assessed the association of ovarian cancer with dietary factors in a population-based case-control study in Canada. Diet information was collected on 442 incident cases of ovarian cancer diagnosed in 1994 to 1997 and 2,135 population controls via a self-administered questionnaire. Compared with women in the lowest quartile of cholesterol intake, those in the second, third, and fourth quartiles had a multivariate adjusted odds ratio [OR; 95% confidence interval (95% CI)] of 1.12 (0.81-1.56), 1.20 (0.85-1.68), and 1.42 (1.03-1.97), respectively (P for trend = 0.031). Higher egg consumption was also associated with a nonsignificant increase in ovarian cancer risk. The ORs (95% CIs) for ovarian cancer were 0.77 (0.60-1.04) and 0.76 (0.56-0.99) among women in the highest quartile of total vegetable and cruciferous vegetable intake as compared with women in the lowest quartile. Women who took supplements of vitamin E, beta-carotene, and B-complex vitamins for > or =10 years had ORs (95% CIs) of 0.49 (0.30-0.81), 0.31 (0.11-0.91), and 0.61 (0.36-1.05), respectively. However, we did not observe an association of ovarian cancer risk with dietary fat intake, including saturated, monounsaturated, and polyunsaturated fatty acids, protein, carbohydrate, dietary fiber, fruit, dairy products, meat products, fish, chicken, grain products, nut products, baked desserts, margarine, butter, mayonnaise, and supplement of multiple vitamins, vitamin A, vitamin C, calcium, iron, zinc, and selenium. Our findings suggested that ovarian cancer risk was positively associated with higher consumption of dietary cholesterol and eggs and inversely associated with higher intake of total vegetables and cruciferous vegetables and supplementation of vitamin E, beta-carotene, and B-complex vitamins.