Search PubMed⌕ Search

Biomedical subjects

T E Rohan

Publications and source records attributed to T E Rohan.

At least 37 records · Page 2Linked to original sources
PubMed2000

A cohort study of nutritional factors and endometrial cancer.

To evaluate the role of nutritional factors in the etiology of endometrial cancer, we performed a case-cohort analysis using data from women enrolled in the National Breast Screening Study in Canada from 1980 to 1985. For this analysis, a subcohort was constructed by selecting a 10% random sample from the 56,837 women in the dietary cohort. Cases were the 221 women diagnosed with incident adenocarcinoma of the endometrium during follow-up to December 31, 1993 and ascertained by record linkage to the Canadian Cancer Database. Information on usual diet at enrollment and other epidemiological variables was collected by means of self-administered questionnaires. Hazard ratios were obtained from proportional hazards regression models, with estimation of robust standard errors. We found a strong association of endometrial cancer with body mass index > 25 kg/m2 (hazard ratio 2.72, 95% CI: 2.06-3.50). Endometrial cancer risk was not associated significantly with intakes of total energy, carbohydrates, proteins, total fat and major fatty acids, total dietary fiber and various types of fibers, vitamin C, E and A, folic acid, beta-carotene, lutein, or cryptoxanthin. Some decrease in risk was noted with relatively high intakes of saturated fat, animal fat or lycopene. The associations observed in the study were independent of total energy intake and most non-dietary risk factors. The study suggests that dietary intakes of energy and most major nutrients are not related to the risk of endometrial cancer among Canadian women.

Adult↗
PubMed2000

Variation in the interaction between familial and reproductive factors on the risk of breast cancer according to age, menopausal status, and degree of familiality.

BACKGROUND: Studies have found that reproductive factors might have a variable effect on the occurrence of breast cancer (BC) according to the existence or not of a family history of BC. The effect of a family history of BC on the risk of BC may also vary according to the age at diagnosis and the degree of kinship. This may confound the relation between familial risk and reproductive factors. A combined analysis was performed to study the interaction between familial risk and reproductive factors according to degree of familiality, age at interview and menopausal status. METHODS: The present analysis included 2948 cases and 4170 controls in seven case-control studies from four countries. The combined relative risks were estimated using a Bayesian random-effects logistic regression model. RESULTS: The main effects of reproductive life factors on the risk of BC are in agreement with previous studies. Two-way interactions between subject's age or menopausal status and a family history of BC were not significant. Although the three-way interaction between age, familial risk and parity was not significant, familial risk seemed to be increased slightly for women with high parity compared with women with low parity in the older age group, and seemed to be slightly decreased for women with high parity compared with women with low parity in younger women. The subject's age also appeared to have an effect on the interaction between familial risk and the age at first childbirth (P = 0.1). CONCLUSIONS: A possible influence of reproductive and menstrual factors on familial risk of BC has been suggested previously and was also evident in the present study. Three-way interactions between age, family history and parity or age at first childbirth might exist and they merit further investigation.

Adult↗
PubMed2000

A cumulative case-control study of risk factor profiles for oncogenic and nononcogenic cervical human papillomavirus infections.

Human papillomaviruses (HPVs) play an essential role in the etiology of cervical cancer, but besides an established role for sexual transmission, little is known about other risk factors for HPV infection. Risk factors for nononcogenic, oncogenic, and HPV 16 cervical infections were investigated using a cumulative case-control approach nested in an ongoing cohort study of low income women from São Paulo, Brazil. HPV DNA was detected and typed by the MY09/11 PCR protocol. Risk factor information was obtained via interviews. In a case-control analysis, we compared women who harbored infections with exclusively nononcogenic types (n = 123), exclusively oncogenic types (n = 94), and any HPV 16 (n = 60) to women remaining HPV-negative (n = 512) throughout 1 year of follow-up. A strong negative association was found between age and oncogenic infections, but not with nononcogenic infections. Oral contraceptive use was strongly and exclusively associated with oncogenic and HPV 16 infections. Markers of sexual activity were associated with all types of infections, although with varying strengths. Our results suggest some important differences in the epidemiological correlates of HPV infection according to oncogenicity that may have implications for the-planning of specific preventive strategies aiming at reduction of cervical cancer risk.

Adolescent↗
PubMed1999

A cohort study of oral contraceptive use and risk of benign breast disease.

The purpose of the cohort study reported here was to investigate the association between oral contraceptive use and risk of benign breast disease (BBD), overall and by histological subtype, within the 56,537 women in 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. Cases were the 2,116 women in the dietary cohort who were diagnosed with biopsy-confirmed incident BBD. For comparative purposes, a subcohort consisting of a random sample of 5,681 women (including 197 subjects with incident BBD) was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 2,116 cases and 5,338 non-cases. There was an inverse association between use of oral contraceptives and risk of all types of BBD combined. The reduction in risk was confined largely to proliferative forms of BBD (BPED), and in particular, to those forms of BPED without histological atypia, in whom there was a progressive reduction in risk with increasing duration of use (the IRR (95% CI) for use of more than 7 years was 0.64 (0.47-0.87)); risk of BPED with atypia was increased somewhat in association with oral contraceptive use (the IRR (95% CI) for use of more than 7 years was 1.43 (0.68-3.01 )), but not in a dose-dependent manner. The results were similar when examined separately in the screened and control arms of the NBSS and for screen-detected and interval-detected BPED.

Adult↗
PubMed1999

Evaluation of human papillomavirus-consensus primers for HPV detection by the polymerase chain reaction.

Cervical cancer is one of the most frequently found cancers in women and appears to have a viral aetiology. Substantial evidence points to the human papillomaviruses (HPV) as the infectious agents and there is considerable interest in identifying and accurately typing the viruses. Since HPVs now comprise more than 100 different HPV types, the polymerase chain reaction (PCR) has been the preferred methodology for virus identification and typing on isolated DNA. In that context, five commonly employed PCR consensus primers have been evaluated for the detection and typing of HPV. The five consensus primer pairs were derived from the consensus sequences of either the L1 and E1 open reading frames. All primers exhibited approximately equal sensitivity, as defined by the ability to detect HPV DNA, on a series of standard HPV DNA-containing preparations. However, the five primer pairs performed differently on 24 HPV-positive and 34 HPV-negative samples obtained from cervical scrapes which had been typed by type-specific PCR for HPV 6/11, 16, 18 and 33. The values for agreement between identification of samples by a HPV type-specific PCR and the consensus primer PCR were 78, 84, 91, 93 and 98%. Three samples, which were positive with only one of the five consensus primer pairs and were negative with the PCR for HPV types 6/11, 16, 18 and 33, contained other HPV sequences or HPV-related sequences as determined by DNA sequence analysis. To our knowledge, this report represents the first extensive comparison of five different consensus primers in a polymerase chain reaction for the detection of HPV. Our results suggest that PCR typing for human papillomaviruses requires more than one consensus primer pair to identify all HPV-infected samples.

Base Sequence↗
PubMed1999

Cigarette smoking and risk of benign proliferative epithelial disorders of the breast.

Benign proliferative epithelial disorders (BPED) of the breast are conditions which are thought to have premalignant potential. The purpose of the present investigation was to study the association between cigarette smoking and risk of BPED. The study was undertaken within the 56,837 women within 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 subcohort consisting of a random sample of 5681 women (including 65 of the subjects with BPED) was selected from the full cohort. After exclusions for various reasons, the analyses were based on 691 cases and 5443 non-cases. Overall, the results of the present study are almost uniformly null, and provide little support for an association between cigarette smoking and risk of BPED. Analyses conducted separately in the screened and control arms of the NBSS also failed to provide strong support for associations, and there was little difference between the results for screen-detected and interval-detected BPED. There was some suggestion of an increase in risk in post-menopausal ex-smokers, but the trend in risk with cigarette-years of exposure in this group was not statistically significant. Risk in ex-smokers varied little by years since smoking cessation. There was little evidence for associations with either atypical or non-atypical forms of BPED.

Adult↗
PubMed1999

Epidemiology of acquisition and clearance of cervical human papillomavirus infection in women from a high-risk area for cervical cancer.

Acquisition and clearance of cervical human papillomavirus (HPV) infection were analyzed among 1425 low-income women attending a maternal and child health program in São Paulo, Brazil. Specimens collected every 4 months were tested by a polymerase chain reaction protocol (MY09/11). In all, 357 subjects were positive at least once. There were 1.3% new infections per month, with 38% cumulative positivity after 18 months. Of 177 positive subjects at enrollment, only 35% remained infected after 12 months. The monthly clearance rate was higher for nononcogenic types (12.2%; 95% confidence interval [CI], 9.6-15.4) than for oncogenic HPV infections (9.5%; 95% CI, 7.5-11.9). Median retention times were 8.1 months (95% CI, 7.8-8.3) for oncogenic types and 4.8 months (95% CI, 3.9-5.6) for nononcogenic HPV infections. The mean infection durations were 8.2 and 13.5 months for nononcogenic and oncogenic types, respectively. Although a woman's age did not affect mean duration for oncogenic types (13-14 months), nononcogenic-type infections lasted longer (10. 2 months) among younger (<35 years old) than in older women (5.6 months).

Adult↗
PubMed1999

Comparison of four habitual physical activity questionnaires in girls aged 7-15 yr.

PURPOSE: Questionnaires provide a practical approach to measuring physical activity in children and adolescents, particularly for large-scale epidemiological studies. The purpose of the present study was to compare four habitual physical activity questionnaires and to assess their long-term reliabilities. METHODS: Subjects were female, aged 7-15 yr (and their parents), who participated in a cohort study in which predictors of the onset of menarche were being investigated. Questionnaires consisted of three single-item and one multi-item habitual physical activity questions and were sent to the 640 participants. Test-retest reliability of the questionnaires was assessed on 100 randomly selected participants 11 months later. RESULTS: The Spearman's correlation coefficient was highest (r = 0.40) between the Godin-Shephard Score and the Perspiration Score and was lowest (r = 0.10) between the Stairs Score and the Specific Activity Score. The correlation coefficients were higher when the questionnaires were reported to have been completed by the parents alone, rather than by parents with the assistance of their daughters. The test-retest reliabilities were r = 0.44 for the Perspiration Score, r = 0.59 for the Stairs Score, r = 0.48 for the Godin-Shephard Score, and r = 0.53 for the Specific Activity Score. The reliabilities were higher when the retest was reported to have been completed by the parents alone. CONCLUSIONS: This study suggests that the Perspiration Score, the Godin-Shephard Score, and the Specific Activity Score may provide simple and practical measures of habitual physical activity for children and adolescents.

Female↗
PubMed1999

Hormone replacement therapy and risk of benign proliferative epithelial disorders of the breast.

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.

Adult↗
PubMed1999

Agreement of self-reported use of menopausal hormone replacement therapy with physician reports.

There have been relatively few epidemiological studies to verify the information obtained from study participants on the use of menopausal hormone replacement therapy. We conducted this study as part of a case-control study of diet, hormone use, and endometrial cancer in Toronto, Ontario, Canada, 1994-1998. We compared records from 653 subjects, 30-79 years of age, with reports from their physicians on ever/never use of hormone replacement therapy and duration, type, and dose of hormone replacement therapy. A total of 88% of the interview records were in agreement with physician reports for ever/never use of hormone replacement therapy. The overall kappa value for ever/never use agreement was 0.76 (range = 0.71-0.81), and the intraclass correlation coefficient was 0.64 (range = 0.57-0.70) for duration of hormone replacement therapy use, indicating good agreement; similar correlations were seen among cases and controls for overall use, as well as estrogen- or progestogen-alone use. Concordance for brand codes was observed for about 43% of the subjects. This study suggests that information obtained by interview in case-control studies provides a reasonable measure of ever use of hormone replacement therapy and duration of use. Interviews, however, do not represent a reliable source of information on brands and dosage of hormone replacement therapy preparations.

Adenocarcinoma↗
PubMed1999

A cohort study of cigarette smoking and risk of fibroadenoma.

BACKGROUND: This cohort study examines the association between cigarette smoking and risk of fibroadenoma. METHODS: The study was conducted among the 56,537 women in the Canadian National Breast Screening Study (NBSS) who completed self-administered lifestyle and dietary questionnaires. (The NBSS is a randomised, controlled trial of screening for breast cancer in women aged 40-59 at recruitment.) Cases were the 222 women who were diagnosed with biopsy-confirmed incident fibroadenoma. For comparative purposes, a subcohort, consisting of a random sample of 5,681 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 222 cases and 5,488 non-cases. Incidence rate ratios (IRR) and 95% confidence intervals (CI) were estimated using Poisson regression. RESULTS: Cigarette smoking was associated with reduced risk of fibroadenoma, the IRR (95% CI) for more than 550 cigarette-years of exposure being 0.66 (0.40-1.10). Although the reduction in risk was evident for all smokers combined (ex-smokers and current smokers), it was indicative largely of an inverse association in current smokers, in whom the IRR (95% CI) for > 300 cigarette-years of exposure was 0.49 (0.24-0.98). The results were mostly the same when examined in strata defined by method of detection of fibroadenoma, menopausal status and history of previous breast disease. There was no evidence for a reduction in risk with time since last use of cigarettes. CONCLUSIONS: The results of this study suggest that cigarette smoking is associated with reduced risk of fibroadenoma, especially in current smokers.

Adult↗
PubMed1999

Markov chain models and estimation of absolute progression rates: application to cataract progression in diabetic adults.

BACKGROUND: We present a case study in the use of Markov chain models of disease progression, with exponential regression to model the effects of covariates. METHODS: An exponential regression model was developed for a three-state Markov chain to model progression of cataracts in diabetic patients, with a view to estimation of absolute progression rates. Two methods of estimation were applied, a non-linear least squares approximation, and Markov Chain Monte Carlo (MCMC). RESULTS: Both methods gave estimated transition rates which can readily be transformed to absolute progression probabilities. Agreement was reasonable for most but not all of the parameters. CONCLUSIONS: The MCMC estimates had more conservative variance estimates.

Aged↗
PubMed1998

Immunohistochemical detection of c-erbB-2 and p53 in benign breast disease and breast cancer risk.

BACKGROUND: We studied the associations between c-erbB-2 protein overexpression and p53 protein accumulation in benign breast tissue and the risk of subsequent breast cancer. METHODS: We conducted a case-control study nested within the cohort of 4888 women in the National Breast Screening Study (NBSS) who were diagnosed with benign breast disease during active follow-up. Case subjects were the women who subsequently developed breast cancer (ductal carcinoma in situ [DCIS] or invasive carcinoma). Control subjects were matched to each case subject on NBSS study arm, screening center, year of birth, and age at diagnosis of benign breast disease. Histologic sections of benign and cancerous breast tissues were analyzed immunohistochemically. Information on potential confounding factors was obtained by use of a self-administered lifestyle questionnaire. RESULTS: Accumulation of p53 protein was associated with an increased risk of progression to breast cancer (adjusted odds ratio [OR] = 2.55; 95% confidence interval [CI] = 1.01-6.40), whereas c-erbB-2 protein overexpression was not (adjusted OR = 0.65; 95% CI = 0.27-1.53). The findings for c-erbB-2 and p53 did not differ among strata defined by menopausal status, allocation within the NBSS, history of breast disease, and whether the benign breast disease was detected at a scheduled screen or between screens. The results were also similar after exclusion of case subjects whose diagnosis of breast cancer occurred within 1 year of their diagnosis of benign breast disease and after exclusion of subjects with DCIS. CONCLUSIONS: p53 protein accumulation, but not c-erbB-2 protein overexpression, appears to be associated with an increased risk of progression to breast cancer in women with benign breast disease.

Adult↗
PubMed1998

A case-cohort study of diet and risk of benign proliferative epithelial disorders of the breast (Canada).

A case-cohort analysis of the association between diet and risk of benign proliferative epithelial disorders (BPED) of the breast was undertaken within a cohort of 56,537 women who were enrolled in the Canadian National Breast Screening Study (NBSS) and who completed a self-administered dietary questionnaire. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40 to 59 years.) BPED are thought to have premalignant potential. Specific hypotheses were that risk of BPED would increase with increasing energy-adjusted fat intake and decrease with increasing energy-adjusted vitamin A and fiber intake. Additionally, we explored the association between calcium intake and risk of BPED. During the active follow-up phase of the NBSS, 657 women in the dietary cohort were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a subcohort consisting of a random sample of 5,581 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 545 cases and 4,921 non-cases. Overall, the results were almost uniformly null, and provided little support for the study hypotheses. Rate ratios (95 percent confidence intervals [CI]) for the highest cf the lowest quintile levels for total fat, retinol, beta-carotene, fiber, and calcium were 0.88 (CI = 0.65-1.20), 0.97 (CI = 0.71-1.31), 0.94 (CI = 0.70-1.27), 1.11 (CI = 0.82-1.50), and 0.81 (CI = 0.60-1.07), respectively. 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 also failed to provide strong support for dietary associations, as did those conducted separately for screen-detected and interval-detected BPED.

Adult↗
PubMed1998

Alcohol consumption and risk of benign proliferative epithelial disorders of the breast: a case-cohort study.

OBJECTIVE: To study the association between alcohol consumption and risk of benign proliferative epithelial disorders (BPED) of the breast (conditions which are thought to have premalignant potential). DESIGN: Case-cohort study. SETTING: The study was undertaken within the 56,537 women in the Canadian National Breast Screening Study (NBSS) who completed self-administered dietary questionnaires. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40-59 years at recruitment.) SUBJECTS: The study subjects were the 657 women in the dietary cohort who were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a subcohort consisting of a random sample of 5681 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 557 cases and 5028 non-cases. RESULTS: When compared to non-drinkers, rate ratios (95% CI) for those consuming > 0 and < or =10 g of ethanol day(-1), >10 and < or =20 g day(-1), >20 and < or =30 g day(-1) and >30 g day(-1) were 0.35 (0.27-0.45), 0.26 (0.18-0.39), 0.29 (0.18-0.48), and 0.23 (0.13-0.40), respectively (the associated P value for the trend was 0.089). Similar findings were obtained from analyses conducted separately in the screened and control arms of the NBSS, in premenopausal and postmenopausal women, and for non-atypical and atypical forms of BPED, and there was little difference between the results for screen-detected and interval-detected BPED. CONCLUSIONS: Alcohol consumption was associated with a non-dose-dependent reduction in risk of BPED.

Adult↗
PubMed1997

Cigarette smoking and risk of prostate cancer: a population-based case-control study in Ontario and British Columbia, Canada.

The relationship between cigarette smoking and risk of prostate cancer was examined in a case-control study conducted in Ontario and British Columbia, Canada. In each centre, cases were men with a histologically confirmed diagnosis of adenocarcinoma of the prostate notified to the provincial cancer registry. In Ontario, controls were selected randomly from assessment lists maintained by the Ontario Ministry of Revenue and were frequency matched to the cases on age. In British Columbia, controls were also frequency matched to the cases on age and were selected randomly from a roster maintained by the Medical Services Plan of British Columbia. The study in Ontario was conducted between April 1990 and April 1992, and that in British Columbia was conducted between January 1989 and December 1991. In all, the study included 408 cases (207 in Ontario and 201 in British Columbia) and 407 controls (207 in Toronto and 200 in British Columbia (one case was unmatched). Overall, there was little variation in risk of prostate cancer with pack-years of cigarette consumption (filter and non-filter cigarettes combined), and there was no evidence for an effect confined to filter or non-filter cigarettes. There was some evidence for a positive association with non-filter cigarettes in British Columbia, but on formal testing for heterogeneity, this finding was not inconsistent with the absence of an association in Ontario. There was also little variation in risk by years since first smoked or (for ex-smokers) by years since quitting. These data provide little support for an association between cigarette smoking and prostate cancer risk.

Adenocarcinoma↗
PubMed1996

Nutritional factors and prostate cancer: a case-control study of French Canadians in Montreal, Canada.

The relationship between the risk of prostate cancer and dietary intake of energy, fat, vitamin A, and other nutrients was investigated in a case-control study conducted in Montreal (Quebec), Canada. French Canadians aged 35 to 84 years with a recent, histologically confirmed diagnosis of adenocarcinoma of the prostate were identified through the admission offices of five major francophone teaching-hospitals in Montreal from 1989 to 1993. Population-based controls matched for age (+/- five years), language, and place of residence were selected by a modified random-digit dialing method. The study included 232 cases and 231 controls. Information on dietary intake was collected by means of a quantitative dietary history. No association was evident between energy intake and the risk of prostate cancer. In contrast, there was some evidence of an inverse association with intake of total fat, animal fat, monounsaturated fat, and particularly saturated fat (odds ratio = 0.69, 95 percent confidence interval = 0.40-1.18, P = 0.05), while a nonsignificant positive association was found with polyunsaturated fat. In addition, high intake of retinol and vegetable protein (highest cf lowest quartile) was associated with reduced risk, but was not statistically significant. No associations were established between intake of other nutrients and risk. These patterns persisted after adjustment for a number of potential confounding factors.

Adenocarcinoma↗