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Biomedical subjects

N F Boyd

Publications and source records attributed to N F Boyd.

117 records · Page 7Linked to original sources
PubMed1979

Pretherapeutic morbidity in the prognostic staging of acute leukemia.

To classify the clinical severity of acute leukemia, we have used the degrees of pretherapeutic infection and hemorrhage to construct a taxonomy containing three "stages". The stages are associated with survival gradients that are clinically and statistically distinctive in both acute lymphoblastic leukemia and acute nonlymphoblastic leukemia. Median survival ranged from 64.0 months for stage 1 to 10.5 months for stage 3 in acute lymphoblastic leukemia, and from 7.1 months for stage 1 to 1.2 months for stage 3 in acute nonlymphoblastic leukemia. The gradients, which persist when other prognostic factors and secular therapeutic changes are taken into account, are more distinctive than those found with other forms of stratification.

Acute Disease↗
PubMedDate not supplied

A method of clinical prognostic staging for patients with rectal cancer.

Methods of prognostic stratification for patients with rectal cancer currently rely solely on the extent of tumor penetration in the surgically excised rectum. Thus stratification according to prognostic factors can be performed only after treatment had been carried out and can play no role in pretherapeutic treatment decisions or in the design of trials of preoperative adjuvant treatment. To devise a method of clinical prognostic staging that could be applied to all patients with rectal cancer, regardless of therapy, the medical records were examined of an inception cohort of 282 patients treated by surgical and nonsurgical methods at three Toronto hospitals during the years 1968 to 1974. Six groups of clinical variables were identified that independently influenced prognosis: the presence or absence of metastatic disease, whether the rectal tumor was fixed or mobile, an annular rectal tumor, and the systemic symptoms of weight loss, anorexia, or weakness, and anemia. A composite method was developed for clinical prognostic staging from these variables and it was found that it created substantial gradients in survival. In patients treated by surgery, for whom comparisons of clinical staging with conventional anatomic staging were possible, clinical staging was as effective a method of prognostic staging as was anatomic staging. Furthermore, the prognostic impact of clinical staging persisted after adjustment for the effects of anatomic staging. This method of clinical prognostic staging should prove useful in making therapeutic decisions and in the design and analysis of clinical trials of alternative treatment for patients with rectal cancer.

Anemia↗
PubMedDate not supplied

Analysis of mammographic density and breast cancer risk from digitized mammograms.

To evaluate the association between mammographic density and breast cancer risk, a simple, observer-assisted technique called interactive thresholding was developed that allows reliable quantitative assessment of mammographic density with use of a computer workstation. Use of this technique helps confirm that mammographic density is one of the strongest risk factors for breast cancer and is present in a large proportion of breast cancer cases. The strong relationship between mammographic density and breast cancer risk suggests that the causes of breast cancer may be better understood by identifying the factors associated with mammographically dense tissue and determining how such tissue changes as these factors vary. Furthermore, because it can be modified, mammographic density may also be a good vehicle for the development and monitoring of potential preventive strategies. Areas of ongoing investigation include evaluating a potential genetic component of mammographic density by comparing density measurements in twins and understanding changes in density relative to age, menopausal status, exogenous hormone use, and exposure to environmental carcinogens. In addition, work is ongoing to establish measurements from imaging modalities other than mammography and to relate these measurements directly to breast cancer risk.

Breast↗
PubMedDate not supplied

Whose utilities for decision analysis?

The goal of this study was to examine sources of variation in the utilities assigned to health states. The authors selected a common clinical problem, carcinoma of the rectum, and examined the utilities assigned to colostomy, a common outcome of treatment for that disease. After preparing and validating a description of colostomy and its effects on patients' lives, utilities for the state were obtained from five groups of individuals. These comprised two groups of patients who received treatment for rectal cancer, a group of physicians and surgeons specializing in the treatment of this disease, and two groups of healthy subjects, none of whom were health professionals. Of the patients who had been treated for rectal cancer, one group had been treated surgically with the formation of colostomies and the other had been treated with radiotherapy and none had a colostomy. Utilities for colostomy were elicited using the standard gamble, category rating, and a treatment choice questionnaire. The groups differed substantially in the utilities assigned to colostomy. In general, patients with colostomies and physicians assigned significantly higher utilities than did patients who did not themselves have a colostomy. The clinical significance of these differences was examined in a simplified clinical decision problem that compared surgery (with colostomy) and radiotherapy (without colostomy) as primary treatment. The expected clinical value of these treatment alternatives was substantially influenced by the differences observed in utilities for colostomy. These results emphasize the importance of patient utilities in clinical decision making and the need to gain greater understanding of the factors that influence the utilities that patients assign to health states.

Attitude of Health Personnel↗
PubMedDate not supplied

Plasma lipids, lipoproteins, and mammographic densities.

There is strong evidence that the risk of breast cancer in populations is influenced by environmental factors. Plasma lipids and lipoproteins are known to be under environmental control and to have epidemiological and/or biological characteristics that suggest they may be relevant to breast cancer risk. The purpose of the study described here was to determine whether plasma lipids, lipoproteins, and the urinary excretion of the mutagen malondialdehyde (MDA) are associated with differences in breast cancer risk. We measured plasma lipids, lipoproteins, and urinary MDA in women without breast cancer but with different degrees of density of the breast parenchyma on mammography, a strong risk factor for breast cancer. Mammograms from 273 premenopausal women were digitized to high spatial resolution by a scanning densitometer, and images were analyzed to quantify the extent of density. The percentage of the breast occupied by mammographic densities was found, after controlling for the effects of age and the Quetelet index of obesity, to be significantly associated with plasma levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, apoprotein B, and urinary excretion of MDA. A multivariate model comprised of the Quetelet index of obesity, alcohol consumption, apoprotein B, parity, daily MDA excretion, and the skinfold thickness sum accounted for 36% of the variation in breast density. These results suggest that differences in lipid metabolism are associated with differences in breast cancer risk as defined by mammographic densities. These findings are consistent with several other observations that show a relationship between plasma lipids, lipoproteins, and risk factors for breast cancer.

Adult↗
PubMedDate not supplied

Canadian recommended nutrient intakes underestimate true energy requirements in middle-aged women.

To examine whether Health Canada's Recommended Nutrient Intakes (RNI) and FAO/WHO/UNU (Food and Agriculture Organization, World Health Organization, United Nations University) values provide accurate indices of true energy requirements, energy expenditure was determined using doubly labelled water (DLW) over 13 days in a group of 29 middle-aged women. Energy intakes were calculated from weighed food intake, and energy expenditures and intakes were then compared with individual calculated RNI requirements. The mean energy requirement as determined by DLW expenditure (9.56 +/- 0.53 MJ/d) was higher (p < 0.0001) than reported energy intake (7.08 +/- 0.30 MJ/d) and was higher (p < 0.004) than RNI mean energy requirement (7.97 +/- 0.18 MJ/d). The mean RNI for energy was also lower (p < 0.0001) than that derived from FAO data. These results suggest that current Health Canada RNIs are inadequate in predicting the energy needs of Canadian middle-aged women.

Adult↗