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Biomedical subjects

L D Marrett

Publications and source records attributed to L D Marrett.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effect of contact letter on control response rates in cancer studies.

Our analysis of response rates for community controls approached in a retrospective study of melanoma indicates that there was an 11 per cent improvement in response rate when the contact letter was changed from inviting participation in a "healthy study" with no mention of cancer to a format which explicitly explained that the study concerned cancer. This improvement was observed for all age-sex groups except younger males. The result suggest that higher response rates may be achieved in studies of cancer if fuller disclosure of the study purposes is made.

Adult↗
PubMed1987

Changing cigarette habits and bladder cancer risk: a case-control study.

With the use of data from the 8,764 subjects in the National Bladder Cancer Study, the separate contribution of various aspects of a person's cigarette smoking history to his increased risk of bladder cancer was estimated. These estimates have not been previously available, owing to the smaller sizes of earlier studies. Our data indicated that people who have only smoked unfiltered cigarettes have higher risks than those who have only smoked filtered cigarettes but that people who have switched from unfiltered to filtered have experienced no reduction in risk. Our data also indicated that smoking cessation substantially reduced the risk. The former smoker appeared to benefit both because he stopped adding to the burden of irreversible damage and because he ceased being exposed to some reversible hazard. Thus the former smoker had a lower risk than the current smoker even though they had smoked the same number of cigarettes daily for the same number of years, but the former smoker's risk remained higher than the risk of a person who never smoked. Our data suggest that one-half of the bladder cancer occurring among men in the United States and one-third of that among women is caused by cigarette smoking.

Adult↗
PubMed1987

Bladder cancer, drinking water source, and tap water consumption: a case-control study.

Data from a population-based case-control interview study of incident bladder cancer in 10 areas of the United States were used to estimate relative risks among white men (2,116 cases, 3,892 controls) and women (689 cases, 1,366 controls) according to beverage intake level and type of water source. Individual year-by-year profiles of water source and treatment were developed by linking lifetime residential information with historical water utility data from an ancillary survey. Risk of bladder cancer increased with intake level of beverages made with tap water. The odds ratio (OR) for the highest vs. lowest quintile of tap water consumption was 1.43 [95% confidence interval (CI) = 1.23, 1.67; chi 2 for trend = 26.3, P less than .001]. The risk gradient with intake was restricted to persons with at least a 40-year exposure to chlorinated surface water and was not found among long-term users of nonchlorinated ground water. The ORs for the highest vs. lowest quintiles of tap water intake were 1.7 and 2.0, respectively, among subjects with 40-59 and greater than or equal to 60 years' exposure. Duration of exposure to chlorinated surface water was associated with bladder cancer risk among women and nonsmokers of both sexes. Among non-smoking respondents with tap water consumption above the population median, the OR increased with exposure duration to a level of 3.1 (CI = 1.3, 7.3; chi 2 for trend = 6.3, P = .01) for greater than or equal to 60 years of residence at places served by chlorinated surface water (vs. non-chlorinated ground water users). These results extend findings of earlier epidemiologic studies and are consistent with environmental chemistry and toxicologic data demonstrating the presence of genotoxic by-products of chlorine disinfection in treated surface waters.

Chlorine↗
PubMed1986

Rates of death from testicular cancer in Ontario in 1964-82: analysis by major histologic subgroups.

In 1977 the rate of death from testicular cancer in Ontario began to decline following a long period of relative stability. This coincided with the addition of cisplatin to the chemotherapeutic regimens used in the treatment of disseminated germ-cell testicular cancer. A study was carried out to determine whether the decline has been similar for the two major histologic subgroups, seminoma and nonseminoma. By means of Ontario Cancer Registry data, histologic type was determined for all testicular cancers causing death in Ontario residents between 1964 and 1982, and death rates were calculated for seminoma and nonseminoma germ-cell testicular cancer. The rates of death from nonseminoma exceeded those from seminoma for the entire study period. Although the death rates for both subgroups declined by about 50% after 1976, the reduction in the overall rate of death from testicular cancer is primarily attributable to the decline in the rate for nonseminoma germ-cell testicular cancer. The increased overall rate of death from testicular cancer (all types) between 1980 and 1984 is cause for concern and indicates the need for continued monitoring of the trends in rates of death from this disease.

Cisplatin↗
PubMed1986

Comparison of risk factors for cervical cancer in different populations.

The incidence of cervical cancer has been found to vary between populations. Risk factors of cervical cancer include early age at first marriage, multiple marriages and antibodies to herpes simplex virus type 2 (HSV-2). The interrelatedness of these risk factors was examined by comparing data collected from 428 cancer cases and 947 control women selected from 6 populations having standardized cervical cancer incidence rates varying from 9.3 to 85.1 per 100,000. Logistic regression analysis revealed that multiple marriages, early age at first marriage or pregnancy and HSV-2 antibodies were all associated with significant risk when all 3 factors were entered into the model. Cervical cancer incidence rates were best predicted by the occurrence of HSV-2 antibodies among control women. To further assess the relation between cervical cancer rates and HSV-2 antibody, 2,306 additional sera representing an 0.8% random sample of females over 9 years of age residing in the Republic of Panama were assayed for antibodies to the virus, and the occurrence of antibodies was correlated with invasive cervical cancer rates specific to each Province. Data from both the random sample and the other study populations yielded a linear relation between the occurrence of HSV-2 antibodies and the incidence of cervical cancer. An exception was found for women living in Herrera Province, Republic of Panama, who had a higher cancer rate than predicted by HSV-2 antibody occurrence. The data suggested that infection with HSV-2 is a co-variable of venereal factors, although a role for the virus in the genesis of a certain proportion of cervical cancers is not excluded.

Adult↗
PubMed1986

Risk factors for adenomatous endometrial hyperplasia: a case-control study.

A population-based case-control study of histologically confirmed endometrial neoplasia was conducted in Toronto, Canada, between 1977 and 1978. Pathologic slide review resulted in classification of patients to diagnostic categories of endometrial carcinoma, endometrial carcinoma in situ, and endometrial hyperplasia. This report concerns the subset of patients classified as having adenomatous endometrial hyperplasia. Two age-matched neighborhood controls were selected for each case, and analyses included only those case-control sets in which the case and at least one control were concordant on menopausal status. Among postmenopausal women (87 cases and 151 controls), noncontraceptive estrogen use was a statistically significant risk factor (adjusted odds ratio (OR) = 6.7), as was heavy body weight relative to height (Quetelet index) (adjusted OR = 3.2). Long-term (5+ years) estrogen use conferred an estimated relative risk of more than 20, but use of oral contraceptives did not alter risk significantly. Among premenopausal women (62 cases and 97 controls), a high Quetelet index appeared to be a significant protective factor, even when adjusted for oral contraceptive use (adjusted OR = 0.2). While oral contraceptive use was not associated with a change in risk, long duration of use was highly, but statistically not significantly, protective against hyperplasia. The data for pre- and postmenopausal women indicate that both endogenous and exogenous estrogen exposure are important factors in the etiology of adenomatous endometrial hyperplasia.

Adult↗
PubMed1986

Bladder cancer and occupational exposure to leather.

A large case-control study of bladder cancer (2982 cases; 5782 controls) included information about occupational exposure to leather. Occupational histories of exposed white study subjects were reviewed and 150 were determined to have had "true" on the job exposure to leather. The odds ratio estimate (OR) of bladder cancer associated with such exposure in white subjects (n = 8063) was 1.4 (95% confidence limits = 1.0, 1.9) after adjustment for sex, age, and cigarette smoking. The risk was highest in those first employed in a leather job before 1945, although no dose-response relation with duration of leather employment was found. Subjects employed in "dusty" leather jobs had a slightly higher risk than those with other types of leather jobs. Our results are consistent with reports of an increased risk of bladder cancer associated with exposure to leather. Although the agents responsible have not been identified, our findings of an increased risk associated with exposure in the earlier years of this century and in dusty jobs suggest that leather dusts may be important.

Adult↗
PubMed1986

Bladder tumor incidence among workers exposed to benzidine: a thirty-year follow-up.

Linkage with records of the Connecticut Tumor Registry was used to determine cancer incidence in a cohort of workers (n = 984) at a benzidine manufacturing facility. Compared to the findings for the Connecticut population, there was a statistically significant excess of bladder tumor among male cohort members [standardized incidence ratio (SIR) = 343; 95% confidence limits (CL) = 148, 676; n = 830], which was confined to those with the highest estimated level of benzidine exposure (SIR = 1,303; CL = 479, 2,839; n = 105). No significantly elevated risks were found for cancers at other anatomic sites in men or at any anatomic sites in women; nor was there any pattern of increasing risk with increasing benzidine exposure for sites other than bladder. In addition, the elevated bladder cancer risk was greater for men first employed during the earliest years of the plant, namely, 1945-49 (SIR = 976; CL = 262, 2,498) as compared to those first employed in 1950-54 (SIR = 213; CL = 3, 1,184) after equalization of duration of follow-up. These results suggest that the major preventive measures instituted around 1950 may have reduced bladder cancer risk in this plant.

Adult↗
PubMed1983

Coffee drinking and bladder cancer in Connecticut.

The association between coffee consumption and bladder cancer is investigated in a population-based case-control study carried out in Connecticut during 1978-1979. Measures of coffee consumption employed include total weekly cups, years of consumption, and more than seven cups per week, in addition to use frequencies of specific coffee types. After adjustment for age and cigarette smoking, a significant elevation in risk for consuming more than seven cups weekly was found for males (odds ratio = 1.5) but not for females (odds ratio = 1.0); there was also some evidence of a dose-response relationship in males. Among nonsmokers of both sexes combined, the odds ratio for more than seven cups per week was 1.9. Male smokers showed age- and smoking-adjusted odds ratios for coffee similar to those of male nonsmokers. Female smokers had a decreased risk for bladder cancer associated with increased coffee consumption which reflects the substantially lowered risk among older (65 years and over) smoking women who may constitute a selected resistant group; odds ratios among younger female smokers were close to 1.0. Males also showed elevated risks associated with consumption of regular (non-decaffeinated) and ground (noninstant) coffees. No relationship with duration of consumption was found.

Adult↗
PubMed1982

Trends in the incidence of cancer of the corpus uteri in Connecticut, 1964-1979, in relation to consumption of exogenous estrogens.

The incidence of cancer of the uterine corpus diagnosed in the localized 1964 and 1969. During the next six years, however, it increased substantially, reaching a peak in 1975, followed by an irregular decline through 1979. Women aged 45-64 years showed both the largest increase and the sharpest decline. The incidence of tumors diagnosed with regional or distant spread has been rising slightly but consistently through the period 1970-1979; this upward trend is statistically significant (p less than 0.01). Rates corrected for hysterectomized women not truly at risk are 40-50% higher than uncorrected rates but trends are the same. Explanations which are considered are changes in diagnostic practices and changes in risk factor prevalence. The use of noncontraceptive oral estrogens, a well documented risk factor for endometrial cancer, increased between 1964 and 1975 and then declined sharply through 1979 in the United States. The importance of these compounds in explaining the observed incidence trends is considered in terms of the major time- and stage-specific features of the exogenous estrogen-endometrial cancer association reported in the case-control studies.

Adult↗
PubMed1982

Use of hair dyes and risk of bladder cancer.

The relation between use of hair dyes and risk of bladder cancer was assessed using data from a case-control study of bladder cancer. Incident cases (2982) and general population controls (5782) were interviewed. The overall estimate of relative risk of bladder cancer for users of hair dyes was 1.0 (95%) confidence interval, 0.9 to 1.2) compared to nonusers. No consistent pattern of association was detected between bladder cancer risk and various indices of timing or intensity of exposure to hair dyes. Various explanations of the lack of association are discussed.

Female↗
PubMedDate not supplied

Methodological issues in the development of the Canadian Cancer Incidence Atlas.

The Canadian Cancer Incidence Atlas is among recent national atlases using incidence rather than mortality data. Methods used to assess the significance and spatial correlation of the age-standardized rates (ASIRs) for the 290 census divisions are described. The expected number of cases by area was used to determine cancer sites with sufficient cases to be mapped. ASIR significance was assessed using a simulation based on a Poisson distribution. The consistency of the observed case distributions with the Poisson distribution was examined. The bootstrap confidence interval (CI) for the ASIR developed by Swift was used in the atlas. Spatial correlation was assessed with Moran's I/I(max) and the significance determined by a simulation in order to allow for area population variation. Data quality indicators typically used for cancer registries were presented, supplemented by a registry questionnaire.

Atlases as Topic↗
PubMedDate not supplied

An analysis of the geographic variation in cancer incidence and its determinants in Ontario.

Cancer incidence data for the Ontario Public Health Units in 1980-91 were examined to investigate regional patterns and the existence of outlier values after adjustment for known risk factors. Candidate risk factors were derived from the Ontario Health Survey and the census. Weighted regressions were fit to the data, and the spatial pattern of the residuals was analyzed. The number of outlier data points with significant elevations or reductions in risk was close to that expected by chance. They were dispersed geographically, and occurred in a variety of cancer types. We conclude that, in general, most of the geographic variation in cancer risk can be associated with variation in known risk factors, and that there appear to be no broad regional effects remaining after adjustment for these factors. A few cancer sites provide limited evidence of regional effects that may warrant further investigation.

Adolescent↗