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Biomedical subjects

A B Miller

Publications and source records attributed to A B Miller.

At least 235 records · Page 13Linked to original sources
PubMed1988

The ethics, the risks and the benefits of screening.

The ethical principles underlying screening are reviewed. It is concluded that the ethical requirements for the introduction of screening are stringent, and that screening should not be offered in the absence of unequivocal evidence of effectiveness except in a carefully conducted research study. Part of the reasons for this are the risks associated with screening, which extend beyond the risk of the test itself, to those associated with invitations for screening, false reassurance for false negatives, the diagnostic process and the problem of false positives, and the overtreatment of those with borderline abnormalities. Finally, the benefits expected from screening are considered, especially reduction in mortality from the disease, but also reduction in incidence if a precursor is detected by the test, less radical treatment for cases detected, reassurance for those who test true negative, and resource savings, though it has to be demonstrated that these exceed resource costs.

Ethics, Medical↗
PubMed1987

An exploratory case-control study of brain tumors in adults.

An exploratory study of brain tumors in adults was carried out using 215 cases diagnosed in Southern Ontario between 1979 and 1982, with an individually matched, hospital control series. Significantly elevated risks were observed for reported use of spring water, drinking of wine, and consumption of pickled fish, together with a significant protective effect for the regular consumption of any of several types of fruit. While these factors are consistent with a role for N-nitroso compounds in the etiology of these tumors, for several other factors related to this hypothesis, no association was observed. Occupation in the rubber industry was associated with a significant relative risk of 9.0, though no other occupational associations were seen. Two previously unreported associations were with smoking nonfilter cigarettes with a significant trend and with the use of hair dyes or sprays. The data do not support an association between physical head trauma requiring medical attention and risk of brain tumors and indicate that exposure to ionizing radiation and vinyl chloride monomer does not contribute any appreciable fraction of attributable risk in the population studied. The findings warrant further detailed investigation in future epidemiologic studies.

Adult↗
PubMed1987

Lung cancer mortality (1950-80) in relation to radon daughter exposure in a cohort of workers at the Eldorado Port Radium uranium mine: possible modification of risk by exposure rate.

A cohort study of 2,103 workers employed between 1942 and 1960 at a uranium mine in the Northwest Territories, Canada, was conducted. A total of 57 lung cancer deaths was observed (expected = 24.73, P less than .0001). There was a highly significant linear relationship between exposure and increased risk of lung cancer, giving estimates for the relative and attributable risk coefficients of 0.27 per working level month (WLM) and 3.10 per WLM per 10(6) person-years. These risk coefficients were substantially less than those estimated from the experience of miners in the Beaverlodge mine, which have previously been reported. Any biases in the present estimates are likely to have been upward, and therefore they probably represent an upper limit. The major difference between the two mine cohorts is in the exposure rate, since the Port Radium miners were exposed to much greater concentrations of radon daughters than the Beaverlodge miners. It is postulated that risk of lung cancer from radon daughter exposure may be modified by exposure rate, for which hypothesis there is some support from other epidemiologic data.

Humans↗
PubMed1987

Consumption of precursors of N-nitroso compounds and human gastric cancer.

It has been hypothesized that dietary nitrate and nitrite are converted in the stomach to nitrous acid, which reacts with secondary amines and amides to form nitrosamines and nitrosamides, compounds frequently demonstrated to be carcinogenic in animals, and that vitamins C and E inhibit N-nitroso product formation by chemically reducing nitrous acid. This hypothesis and others were tested in a case-control study (controls were individually matched by age, sex and area of residence), utilizing a standardized, quantitative, dietary history questionnaire interview. Daily nutrient consumption values were calculated from interview responses, and continuous conditional logistic regression was used for the data analysis. Significant findings are as follows: (1) Average daily consumption of nitrite, chocolate and carbohydrate was associated with increasing trends in risk. (2) While citrus fruit intake appeared to be somewhat protective, any protective effect of vitamin C intake was less apparent, and of vitamin E, not at all apparent. (3) Consumption of dietary fibre was negatively associated with gastric cancer risk. These findings appear to implicate a number of dietary components, including nitrite consumption, in the genesis of gastric cancer in humans.

Adult↗
PubMed1986

Selection of women at high risk of breast cancer for initial screening.

Selective breast cancer screening refers to the intentional restriction of screening to only a high-risk subgroup of the total population of women at risk. Using data from the Canadian National Breast Screening Study, we explored methods of defining such subgroups. Discriminants were based on risk factor information collected prior to screening and were constructed using a training group of 77 cases and 400 controls. They were then tested on a separate group of 38 cases and 200 controls. Both simple risk factor counts and logistic models were utilized and separate analyses were performed for pre- and post-menopausal women. Using a logistic model, we were able to define a high-risk subgroup encompassing less than 40% of the test controls and over 85% of the test cases. Such a selection strategy, if implemented, might reduce initial visit mammography rates by up to 60% with only a small reduction in case detection. Other uses as determining the optimal age for initiation of screening are also discussed.

Age Factors↗
PubMed1986

A study of the effect of weight and dietary fat on breast cancer survival time.

Female breast cancer patients who had participated in a case-control study conducted during 1973-1975 were followed up, using record linkage to the Statistics Canada mortality data base, to the end of 1980. A number of variables recorded for the case-control study, in particular body weight and daily intake of dietary fat near the time of diagnosis, were examined to see if they had any bearing on breast cancer mortality. The data were analyzed using the methods of Mantel and Cox. Dietary fat was not found to be related to patient survival. However, cases with greater than average body weight experienced a shortened survival time.

Adult↗
PubMed1986

Sensitivity and specificity of first screen mammography in the Canadian National Breast Screening Study: a preliminary report from five centers.

Sensitivity and specificity of first screen mammography in a randomized screening trial at five centers are reported. A total of 23,101 women underwent mammography; in 139, breast cancer was detected at first screening; in 20, less than 12 months after first screening; and in 47, at second screening. All 206 cancer cases were histologically confirmed, and 174 were defined as being detectable at first screening. Average length of follow-up for all women was 3.2 years. Interpretations of first screen mammograms by the center radiologists were matched to known outcomes. Simultaneous blind review was performed by a single reference radiologist with mammograms from all 206 cancer cases and those of a random sample of 739 women not known to have breast cancer at 15 months or more after initial screening. Overall, the five screening centers achieved a sensitivity of 69% (range, 60%-78%), a specificity of 94% (range, 93%-96%), a positive predictive value of 8.6% (range, 3%-16%), and a negative predictive value of 99.7% (range, 99.6%-99.9%).

Breast Neoplasms↗