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Biomedical subjects

T E Rohan

Publications and source records attributed to T E Rohan.

At least 19 recordsLinked to original sources
PubMed1992

Oral contraceptives and risk of benign proliferative epithelial disorders of the breast.

In a case-control study conducted in Adelaide, South Australia, we investigated the hypothesis that use of oral contraceptives is associated with increased risk of benign proliferative epithelial disorders (BPED) of the breast, conditions strongly associated with increased risk of breast cancer and thought to have pre-malignant potential. The study was restricted to women with no prior history of breast biopsy, and involved 383 cases of biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls individually matched to cases by age and socio-economic grading of area of residence. When cases were compared with community controls, the adjusted odds ratio (OR) for the association between ever-use of oral contraceptives and risk of BPED was 1.1 (95% CI 0.7 to 1.7), while when cases were compared with biopsy controls, the adjusted OR was 0.9 (95% CI 0.5 to 1.5). There was little variation in risk of BPED with total duration of use of oral contraceptives, and with duration of use before first pregnancy, while current users had a statistically significant 60% reduction in risk, irrespective of the control group used for comparative purposes. Also, there was little variation in risk with years since first and last use of oral contraceptives, and there was no trend in the association between ever-use of oral contraceptives and risk of BPED by degree of cytological atypia.

Adult↗
PubMed1992

Risk factors for fibroadenoma: a case-control study in Australia.

Risk factors for fibroadenoma were examined in a case-control study involving 117 fibroadenoma cases ascertained by a major private pathology laboratory in Adelaide, Australia, between January 1983 and October 1985. For each case a population control was randomly selected from the electoral roll in Adelaide and matched to the corresponding case by sex, age, and socioeconomic grading of area of residence. Another 189 women whose first biopsy for benign breast disease was examined in the same laboratory during the same time period as those of the cases, but did not show evidence of epithelial proliferation, were also included in the study as a biopsy control group. Risk of fibroadenoma was associated inversely with the Quetelet index, but there was no evidence of an association with age at menarche or menopausal status. The risk of fibroadenoma decreased with an increasing number of full-term pregnancies and was increased in association with use of oral contraceptives at an early age (under 20 years); however, these two associations were observed only when cases were compared with the population controls. Alcohol consumption and dietary fat intake were found not to be associated with altered risk of fibroadenoma, while in multivariate analyses, duration of cigarette smoking and daily vitamin C intake were both shown to have inverse associations with risk of fibroadenoma. Although fibroadenoma does share some risk factors with breast cancer, there is insufficient evidence to suggest that it represents a precursor state.

Adenofibroma↗
PubMed1991

Repeat measurement of case-control data: correcting risk estimates for misclassification due to regression dilution of lipids in transient ischemic attacks and minor ischemic strokes.

In a case-control study to determine the role of lipids as risk factors for ischemic cerebrovascular disease, 105 cases of transient ischemic attacks and minor ischemic strokes were compared with 241 controls. Recruitment to the study took place in Oxford, United Kingdom, in 1986 and 1987. In a random subset of 100 of the original controls, repeat assays of total cholesterol, low density lipoprotein cholesterol, (LDL cholesterol), and high density lipoprotein cholesterol (HDL cholesterol) were performed. With maximum likelihood theory, the repeat data were used to produce odds ratio estimates of relative risk corrected for mismeasurement. Uncorrected odds ratios associated with total cholesterol of more than 6 mmol/liter, LDL cholesterol of more than 3.5 mmol/liter, and HDL cholesterol of more than 1.2 mmol/liter were, respectively, 2.06 (95% confidence interval (CI) 1.26-3.37), 2.02 (95% CI 1.24-3.30), and 0.46 (95% CI 0.28-0.74). Corrected for mismeasurement, the corresponding odds ratios were 2.90 (95% CI 1.42-5.93), 2.57 (95% CI 1.24-5.32), and 0.36 (95% CI 0.17-0.71), respectively. The attributable risks changed from 34 to 48% for total cholesterol, from 34 to 43% for LDL cholesterol, and from 35 to 45% for HDL cholesterol. The maximum likelihood procedure described here corrects for substantial underestimation of the strength of an association and indicates the need to obtain repeat measurements on variables which are subject to random fluctuation.

Case-Control Studies↗
PubMed1991

Benign breast disease: the relationship between its histological features and risk factors for breast cancer.

Associations between histologically defined proliferative, but benign, epithelial disorders of the breast and risk factors for breast carcinoma were examined in 568 patients whose breast biopsies were submitted consecutively to the laboratory. Some disorders were associated with multiparity. Blunt duct adenosis was associated with a family history of breast cancer. Apart from a positive association with fibroadenoma, use of oral contraceptives was not associated with any proliferative lesion. Proliferative epithelial lesion changes were not associated with other aspects of obstetric or gynecological history.

Adult↗
PubMed1990

A case-control study of diet and benign proliferative epithelial disorders of the breast.

Benign proliferative epithelial disorders (BPED) of the breast are conditions which, although not proven precursors of breast cancer, are strongly associated with increased risk of this disease. In a case-control study conducted in Adelaide, South Australia, we investigated the association between dietary factors and risk of BPED. The study involved 383 cases of biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls matched to cases on age and area of residence. When cases were compared with community controls, there was little variation in the risk of BPED across levels of daily intake of energy, protein, and fat, but there was some suggestion of inverse associations with daily intake of retinol, beta-carotene, and fiber; in contrast, with biopsy controls as the comparison group, risk of BPED increased with increasing energy and fat intake but varied little with retinol, beta-carotene, and fiber intake. The results of this study provide additional evidence against roles for dietary energy and fat intake in the etiology of breast cancer. However, further studies of diet and BPED should be conducted in populations surveyed cross-sectionally for breast changes, in an attempt to limit or avoid the selection and misclassification biases to which studies of putative precursor lesions are susceptible.

Adult↗
PubMed1989

Prevention of blindness by screening for diabetic retinopathy: a quantitative assessment.

Diabetic retinopathy is an important cause of blindness in the Western World. A review of the randomised trials of laser photocoagulation of the retina as a method of preventing blindness from this disorder showed that this treatment is very effective, reducing the risk of blindness by 61% in a treated eye. As only one eye is needed for sight the reduction in blindness in a population will be greater than 61% because the effect of treatment in one eye is not always identical with the effect in the other eye. For analysis this reduction was taken as 73%, representing the average of the minimum and maximum estimates (61% and 85%). The effectiveness of this treatment suggests that there is the potential for a national screening programme to bring about a major reduction in blindness from this cause. A quantitative assessment of the effect of screening indicated that a programme in which patients with diabetes mellitus are systematically referred to ophthalmic opticians for a retinal examination could detect 88% of all diabetics with serious retinopathy and that 87% of these cases would be treatable. Screening and early treatment of retinopathy would prevent deterioration of visual acuity and could reduce the risk of blindness due to diabetic retinopathy by an estimated 56% (0.73 X 0.88 X 0.87). The findings suggest that an effectively managed community based screening programme encompassing detection, referral, treatment, and follow up would prevent about 260 new cases of blindness in diabetics under the age of 70 each year in England and Wales. This would represent over 10% of all cases of blindness in adults in this age group.

Blindness↗
PubMed1989

Risk of bladder cancer by source and type of tobacco exposure: a case-control study.

The association between tobacco use and risk of bladder cancer was investigated in a population-based case-control study conducted in Alberta and south-central Ontario, Canada, between 1979 and 1982. In all, 826 histologically-confirmed cancer cases and 792 randomly selected controls, individually matched to cases for age, sex, and area of residence, were recruited into the study. Compared to those who had never smoked cigarettes, males and females who had ever smoked cigarettes had a statistically highly significant 2-fold increase in risk of bladder cancer; for ex-smokers, the risk was intermediate between that for current smokers and never-smokers. There was a dose-dependent increase in risk of bladder cancer with total lifetime cigarette consumption, of similar magnitude for males and females. In males, risk increased with self-reported degree of inhalation in ex-smokers and in current smokers (statistically significant trend), while in females there was no association in current smokers, and a statistically significant inverse association in ex-smokers. Overall, risks of bladder cancer associated with lifetime consumption of plain and filter cigarettes were similar, and there was little evidence to suggest that switching from plain to filter cigarettes was beneficial. Neither passive smoking nor other forms of tobacco consumption (pipes, cigars, chewing tobacco, or snuff) were associated with altered risk of bladder cancer. The population attributable risk for cigarette smoking was about 47% in males and about 33% in females.

Adult↗
PubMed1989

Alcohol consumption and risk of benign proliferative epithelial disorders of the breast in women.

Many studies have shown a positive association between alcohol consumption and risk of breast cancer. Benign proliferative epithelial disorders (BPED) of the breast are conditions which, although not proven precursors of breast cancer, are strongly associated with increased risk of this disease. The association between alcohol consumption and risk of BPED was examined in a case-control study conducted in Adelaide, South Australia. The study involved 383 cases with biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls individually matched (I:I) to cases on age and area of residence. When cases were compared with community controls, the unadjusted relative risk of BPED for drinkers versus non-drinkers was 0.9 (95% CI 0.6-1.3), and the corresponding relative risk derived from comparing cases with biopsy controls was 1.0 (95% CI 0.6-1.4); these estimates were not altered after adjustment for potential confounding. Variation in risk of BPED across levels defined in terms of daily total alcohol intake, and in terms of daily alcohol intake from individual beverages, was mostly insubstantial and not dose-dependent. Also, there was little variation in risk with age at first drink, or by current drinking status, and risk of BPED in association with alcohol consumption did not increase with severity of cytologic atypia. Despite the absence of an association in this study, further investigation is warranted, since it may provide opportunities for the prevention of BPED and of breast cancer.

Adolescent↗
PubMed1989

Misclassification in more than one factor in a case-control study: a combination of Mantel-Haenszel and maximum likelihood approaches.

Misclassification can arise in the case-control setting in both the risk factor of interest, and in a potential confounder. If true status is not ascertainable, but an independent replicated sample is available, adjusted maximum likelihood estimates of the individual binomial proportions can be obtained, and hence a relative risk estimate of the Mantel-Haenszel type constructed. An interval estimate on the latter can be calculated using the asymptotic properties of the likelihood function. The method is illustrated by application to a case-control study of breast cancer risk and such lifestyle attributes as diet, smoking and alcohol consumption, in which misclassification was anticipated and consequently repeatability data were collected.

Breast Neoplasms↗
PubMed1989

Risk factors for breast cancer by oestrogen receptor status: a population-based case-control study.

Data from a population-based case-control study conducted in Adelaide, South Australia, and involving 451 case-control pairs, were analysed to determine whether the associations of menstrual, reproductive, dietary and other factors with risk of breast cancer differed by oestrogen receptor (ER) status. Data on ER status were available for 380 cases. The proportion of tumours which were ER+ increased with age, and there was a higher proportion of ER+ tumours in post-menopausal than in premenopausal women. Both oral contraceptive use (P = 0.055) and cigarette smoking (P = 0.047) were associated with increased (unadjusted) risk of ER- cancer, while having little association with risk of ER+ cancer. Most dietary factors had little association with risk of either cancer type, the main exception being the reduction in risk of ER- breast cancer with increasing beta-carotene intake (P for trend = 0.017). In general, however, links with the factors examined were not strong enough to suggest different causal pathways for ER- and ER+ breast cancer.

Adult↗
PubMed1989

Methylxanthines and benign proliferative epithelial disorders of the breast in women.

The relationship between methylxanthine intake (caffeine, theobromine and theophylline) and risk of benign proliferative epithelial disorders (BPED) of the breast was examined in a case-control study conducted in Adelaide, South Australia. The study involved 383 cases with biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls individually matched to cases on age and area of residence. Overall, there was relatively little variation in risk of BPED with total methylxanthine intake, or with intake of caffeine or theophylline, while there was a positive association between theobromine intake and risk of BPED, but only when cases were compared with biopsy controls. Total methylxanthine intake was positively associated with risk of BPED showing severe atypia, but the trend in risk was statistically significant only when community controls formed the comparison group. These data do not provide strong support for an association between methylxanthine intake and risk of BPED.

Adolescent↗
PubMed1989

Cigarette smoking and breast cancer.

The relation between cigarette smoking and the risk of breast cancer in women was investigated in a population-based case-control study conducted in Adelaide, Australia during 1982-1984. Cases were identified through the South Australian Central Cancer Registry, and, for each case, one age-matched control was selected from the electoral register; in all, 451 case-control pairs were enrolled. Overall, no clear association was found between ever or current smoking and breast cancer risk. In a subgroup analysis, premenopausal ex-smokers were observed to have an increased risk (estimated odds ratio = 2.3). The absence of a protective effect of cigarette smoking on breast cancer risk may reflect the relatively weak estrogen dependence of breast cancer, or the nature of its hormone dependence.

Adult↗
PubMed1989

A method for combining matched and unmatched binary data. Application to randomized, controlled trials of photocoagulation in the treatment of diabetic retinopathy.

A method for combining matched and unmatched data is described and was applied to the results of randomized, controlled trials of photocoagulation in the treatment of diabetic retinopathy. A pooled estimate from the matched and unmatched studies was obtained by adaptation of the Mantel-Haenszel method, where the strata were unmatched studies and matched pairs within studies. A test of significance was based on the Mantel-Haenszel chi-square statistic, the latter also being used to calculate test-based confidence intervals. A test of homogeneity was performed by combining Mantel-Haenszel chi-square statistics from the matched and unmatched studies. By these methods, the combined estimate of the risk of deterioration of visual acuity for those receiving photocoagulation (relative to a risk of unity for those not receiving photocoagulation) was 0.37 (95 per cent confidence interval 0.29-0.46). The chi-square statistic (1 df) for an effect of treatment was 87.75 (p less than 0.0001). The chi-square statistic for homogeneity of relative risk among studies was 11.20 (4 df, p less than 0.05). However, this result was influenced disproportionately by one small matched study.

Diabetic Retinopathy↗
PubMed1989

Cigarette smoking and benign proliferative epithelial disorders of the breast in women: a case-control study.

STUDY OBJECTIVE: The purpose of the study was to investigate the possible association between cigarette smoking and benign proliferative epithelial disorders of the breast. DESIGN: This was a case-control study with two different control groups. SETTING: The study was community based and took place in metropolitan Adelaide, South Australia. SUBJECTS: 506 biopsy proven cases between 18 and 75 years were identified, of whom 39 could not be approached because of surgeon refusal, 66 would not be interviewed and 18 were untraceable, leaving 383 for inclusion in the study. Controls were 192 women who had had a negative breast biopsy, out of a possible 259 (17 surgeon refusals, 39 interview refusals, 11 untraceable); and a randomly selected group of women matched to the index group for age and area of residence (582 subjects were approached to enrol 383 controls). MEASUREMENTS AND MAIN RESULTS: All breast biopsies were examined by one pathologist and classified using a standard system. Sociodemographic and medical information was collected by trained interviewers using structured questionnaires. Overall, and within menopausal strata, risk of benign proliferative epithelial disease for women who had ever smoked and for current and ex-smokers was similar to that for women who had never smoked. In premenopausal women, using community controls as the comparison group, risk decreased with cigarette-years of exposure, but the trend was not statistically significant. Risk appeared to increase when biopsy controls were used. There was no trend in the association when examined by degree of cytological atypia. CONCLUSIONS: The data suggest that cigarette smoking is not related to the risk of benign proliferative epithelial breast disease.

Adolescent↗
PubMed1988

Oral contraceptive agents and breast cancer: a population-based case-control study.

In this population-based case-control study that was conducted in Adelaide, South Australia, and which involved 395 case subjects and 386 control subjects who were aged 20 years to 69 years, the adjusted relative risk of breast cancer for women who had ever used oral contraceptive agents was 1.06 (95% confidence interval [CI], 0.70-1.60). Relative risks that were associated with use of oral contraceptive agents for one month to 18 months and for 19 months or more before a first pregnancy were 1.09 (95% CI, 0.45-2.62) and 1.67 (95% CI, 0.63-4.42), respectively, but the trend was not statistically significant. Relatively-little variation in risk was found in association with the total duration of the use of oral contraceptive agents and with years since the first and the last use of oral contraceptive agents. When the risk of breast cancer in association with the use of oral contraceptive agents was examined across levels of risk factors of breast cancer (history of benign breast disease, family history of breast cancer and parity), the only relative risk which deviated markedly from unity was that which was associated with use of oral contraceptive agents in women with a history of benign breast disease; however, the relative risk of 1.77 (95% CI, 0.35-8.97) was not statistically significant. In conclusion, the results of this study support those of the majority of previous studies in showing no overall relationship between the use of oral contraceptive agents and the risk of breast cancer.

Adult↗
PubMed1988

Alcohol consumption and risk of breast cancer.

In a population-based case-control study conducted in Adelaide, South Australia, and involving 451 case-control pairs aged 20-74 years, the risk of breast cancer for women consuming more than 9.3 g of alcohol per day was 50% higher than for non-drinkers (unadjusted RR 1.46, 95% CI 1.00-2.13). The increase in risk persisted upon control for potential confounding variables including dietary or diet-related factors, and was not restricted to any particular type of beverage. Lower levels of alcohol consumption were not associated with substantial alterations in risk of breast cancer. When examined within menopausal strata, the effect of alcohol was more pronounced in pre-menopausal women, although none of the estimates of effect within menopausal strata were statistically significant. Although positive associations between alcohol consumption and risk of breast cancer have been observed in previous studies, support for a causal association is, at most, qualified. However, given the widespread nature of this exposure, at least in developed countries, further and more detailed investigations of this association are required.

Adult↗
PubMed1988

Methylxanthines and breast cancer.

The association between intake of methylxanthines and risk of breast cancer was examined in this population-based case-control study conducted in Adelaide, South Australia. The study included 451 cases, and one control was matched to each case for age (to the nearest year). Overall, and within the post-menopausal stratum, there was relatively little variation in the risk of breast cancer in association with total caffeine and total methylxanthine intake. In pre-menopausal women, risk was increased at the higher levels of intake, but the increase in risk was not dose-dependent. There was no evidence for an effect of methylxanthines at high levels of fat intake. Prior epidemiological and experimental studies have not provided strong support for a positive association between intake of methylxanthines and risk of breast cancer. However, the possibility that they are linked through an association between methylxanthines and those histological subcategories of benign breast disease which are strongly associated with risk of breast cancer is discussed.

Adult↗