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N Kreiger

Publications and source records attributed to N Kreiger.

53 records · Page 3Linked to original sources
PubMed1993

An historical cohort study of cardiac catheterization during childhood and the risk of cancer.

This study aimed to determine whether cancer risk was elevated among patients exposed to radiation from diagnostic cardiac catheterization during childhood. The study cohort included 3915 children who underwent at least one cardiac catheterization at a major children's hospital in Toronto, Canada, between 1950 and 1965, were < or = 18 years at the time of the procedure, and were residents of Ontario. Follow-up of the cohort was done by linkage to the Ontario Cancer Registry up to 1986. A total of seven cancer deaths were observed (O), compared with 5.7 expected (E) based on provincial cancer rates (mortality ratio [O/E] = 1.2; 90% confidence interval [CI] : 0.6-2.3). In the analysis of cancer incidence, 13 cancers were detected, compared with 17.3 expected (O/E = 0.75; 90% CI : 0.4-1.2). These mortality and incidence ratios were not statistically significantly elevated. Detailed analyses were conducted according to age at exposure, age at diagnosis, sex, number of procedures, year of first catheterization, and latent period. Detected deviations in risk were confined to an early period of exposure, indicating that later practices of cardiac catheterization were not associated with increased risk. In general, there was no statistically significant excess risk of cancer among the cohort.

Adolescent↗
PubMed1992

The effect on response rates of offering a small incentive with a mailed questionnaire.

To determine whether response rates to a mailed questionnaire sent to population control subjects could be increased through offer of a small incentive, half of the control subjects (n = 477) in a case-control study of renal cell carcinoma were randomly selected to receive a contact letter offering a lottery ticket if a completed questionnaire was returned; the remaining subjects (n = 477) received the same letter but with no mention of a lottery ticket. Overall response rates did not differ between the two groups (72.6% versus 74.4%), although a higher percentage of those offered a lottery ticket responded without follow-up (24.4% versus 18.5%). Binomial regression modeling of the effect of the lottery ticket offer, sex, age, and percent of urban dwellers on response indicated a significant effect only for percent of urban dwellers, the rate of response increasing with a decreasing percentage of urban dwellers. The effect of sex was of borderline significance (P = 0.05), with females having the higher rate of response.

Adult↗
PubMed1992

Dietary factors and fracture in postmenopausal women: a case-control study.

This case-control study examined the effect of diet on the risk of postmenopausal fracture of the hip and wrist. Cases, women aged 50-84 years, were admitted to one of four Metropolitan Toronto hospitals during the period September 1983 through May 1985. Controls were women of the same age, admitted to the same hospitals, and seen for orthopaedic or general surgical complaints. Data were collected through the use of a standardized structured questionnaire administered by trained female interviewers, and included dietary, sociodemographic, medical, and behavioural variables. Data analysis was conducted on 102 hip fracture cases, 154 wrist fracture cases, and 277 controls. Higher dietary calcium intake only slightly increased the risk of hip fracture; however, it was associated with a significantly decreased risk for fracture of the wrist, at the level > or = 1 g/day. Coffee and tea consumption appeared to be unrelated to fracture risk. Finally, alcohol intake was associated with a statistically nonsignificant increased risk in both fracture types. These findings point to the importance of dietary factors on fracture risk, and indicate a need for future studies to stratify analysis on the basis of fracture type.

Aged↗
PubMed1991

Cancer incidence registration and trends in Ontario.

The Ontario Cancer Registry (OCR) contains information on the incidence, mortality and survival of cancer in Ontario. The OCR refers to the population of Ontario, which is currently more than 9 million people. Cancer registration is accomplished by the computerised linkage of records collected routinely for other purposes. Incidence data are available from the OCR beginning in 1964. Incidence rates, age-standardised to the World Standard Population, are presented for Ontario in two recent 5-year periods (1979-1983 and 1984-1988). Age-specific rates are also presented for selected sites. The most common cancer sites, in terms of Ontario incidence rates, were similar to those reported from other registries. In males, these were cancers of the lung, prostate, colon, bladder and rectum. In females, these were cancers of the breast, lung, colon, body of the uterus and ovary. The potential effects of changes in medical services, screening practices and risk factor prevalence on the incidence rates and trends are discussed.

Adolescent↗
PubMed1991

Steroid receptor status and the epidemiology of breast cancer.

This case-control study examined risk factors for breast cancer according to tumor estrogen receptor (ER) status and progesterone receptor (PR) status. The data included 607 case patients and 1214 control subjects matched by age and residence. Of 528 case patients with steroid receptor information, 67% had ER-positive tumors and 55% had PR-positive tumors. Odds ratios for ER-positive and ER-negative breast cancer were similar with respect to menopausal status, age at menarche, history of cystic breast disease, and Quetelet Index. Family history of breast cancer was a stronger risk factor for ER-negative than for ER-positive breast cancer and the odds ratios for number of births were suggestive of a different effect. While ER and PR status were highly correlated, there were some differences in their associations with risk factors. Odds ratios for PR-positive and PR-negative breast cancer differed for number of births and were suggestive of differences with respect to menopausal status, Quetelet Index, and family history of breast cancer. These findings do not suggest different causal pathways for ER-positive and ER-negative breast cancer. However, they do indicate that PR status may play a role in the etiology of breast cancer.

Adult↗
PubMed1989

Radiation dose and breast cancer risk in patients treated for cancer of the cervix.

The relationship between breast cancer and radiation treatment for cervical cancer was evaluated in an international study of 953 women who subsequently developed breast cancer and 1,806 matched controls. Radiation doses to the breast (average 0.31 Gy) and ovaries (average 32 Gy) were reconstructed for exposed subjects on the basis of their original radiotherapy records. Overall, 88% of the breast cancer cases and 89% of the controls received radiation treatment [relative risk (RR) = 0.88; 95% confidence interval (CI) = 0.7-1.2]. Among women with intact ovaries (561 cases, 1,037 controls), radiotherapy was linked to a significant 35% reduction in breast cancer risk, attributable in all likelihood to the cessation of ovarian function. Ovarian doses of 6 Gy were sufficient to reduce breast cancer risk but larger doses did not reduce risk further. This saturation-type response is probably due to the killing of a critical number of ovarian cells. Cervical cancer patients without ovaries (145 cases, 284 controls) were analyzed separately because such women are at especially low natural risk for breast cancer development. In theory, any effect of low-dose breast exposure, received incidentally during treatment for cervical cancer, should be more readily detectable. Among women without ovaries, there was a slight increase in breast cancer risk (RR = 1.07; 95% CI = 0.6-2.0), and a suggestion of a dose response with the RR being 1.0, 0.7, 1.5 and 3.1 for breast doses of 0, 0.01-0.24, 0.25-0.49 and 0.50+ Gy, respectively. However, this trend of increasing RR was not statistically significant. If low-dose radiation increases the risk of breast cancer among women over age 40 years, it appears that the risk is much lower than would be predicted from studies of younger women exposed to higher doses.

Adult↗
PubMed1988

Radiation dose and second cancer risk in patients treated for cancer of the cervix.

The risk of cancer associated with a broad range of organ doses was estimated in an international study of women with cervical cancer. Among 150,000 patients reported to one of 19 population-based cancer registries or treated in any of 20 oncology clinics, 4188 women with second cancers and 6880 matched controls were selected for detailed study. Radiation doses for selected organs were reconstructed for each patient on the basis of her original radiotherapy records. Very high doses, on the order of several hundred gray, were found to increase the risk of cancers of the bladder [relative risk (RR) = 4.0], rectum (RR = 1.8), vagina (RR = 2.7), and possibly bone (RR = 1.3), uterine corpus (RR = 1.3), cecum (RR = 1.5), and non-Hodgkin's lymphoma (RR = 2.5). For all female genital cancers taken together, a sharp dose-response gradient was observed, reaching fivefold for doses more than 150 Gy. Several gray increased the risk of stomach cancer (RR = 2.1) and leukemia (RR = 2.0). Although cancer of the pancreas was elevated, there was no evidence of a dose-dependent risk. Cancer of the kidney was significantly increased among 15-year survivors. A nonsignificant twofold risk of radiogenic thyroid cancer was observed following an average dose of only 0.11 Gy. Breast cancer was not increased overall, despite an average dose of 0.31 Gy and 953 cases available for evaluation (RR = 0.9); there was, however, a weak suggestion of a dose response among women whose ovaries had been surgically removed. Doses greater than 6 Gy to the ovaries reduced breast cancer risk by 44%. A significant deficit of ovarian cancer was observed within 5 years of radiotherapy; in contrast, a dose response was suggested among 10-year survivors. Radiation was not found to increase the overall risk of cancers of the small intestine, colon, ovary, vulva, connective tissue, breast, Hodgkin's disease, multiple myeloma, or chronic lymphocytic leukemia. For most cancers associated with radiation, risks were highest among long-term survivors and appeared concentrated among women irradiated at relatively younger ages.

Female↗
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↗
PubMed1984

Second primary cancer following treatment for cervical cancer.

A follow-up study of 7535 women in Ontario was carried out to assess the occurrence of second primary cancers following the treatment of invasive carcinoma of the cervix between 1960 and 1975. The study was part of a larger international investigation of late radiation effects in patients with cervical cancer. Data were collected on the date and the type of treatment for cervical cancer and on the occurrence of second primary cancers diagnosed before 1980. Observed and expected numbers of second primary cancers, the latter determined according to Ontario incidence rates, were compared for individual sites and for all sites combined. There were significantly more primary cancers of the lung than expected (64 v. 15.52) but significantly fewer second primary cancers of the breast (56 v. 105.01) and colon (27 v. 43.31). Overall, there were significantly fewer (p less than 0.05) observed second primary cancers than expected (280 v. 394). Although the median follow-up period was less than 10 years there was no marked evidence of an excess of radiation-induced second primary cancers.

Carcinoma↗
PubMed1982

An epidemiologic study of hip fracture in postmenopausal women.

In this case-control study of the epidemiology of hip fracture in post-menopausal women aged 45-74 years, cases of hip fracture and two control groups were selected from admissions to four general hospitals in Connecticut between September 1977 and May 1979. Fewer cases of hip fracture than controls had been exposed to estrogen replacement therapy, and among those who had been exposed, exposure time was shorter than that for controls. The cases had breastfed their children for shorter durations, and they more often had had both ovaries removed. Also, the cases were found to weigh less than the controls. The negative associations of hip fracture with estrogen replacement therapy, intact ovaries, and weight are consistent with the hypothesis that estrogens protect against hip fracture.

Aged↗
PubMed1981

Injuries to the upper extremity: patterns of occurrence.

Injuries to the upper extremity, as reported in home interviews, physician office records, and hospital records, are a problem of great magnitude. Upper extremity injuries not only are responsible for a great deal of disability and for a large number of visits for medical care, but also, because they often affect people of working age, have a great impact on society because of loss of productivity. However, regardless of the age at which they occur, these injuries can have an impact on the quality of life of the injured, both in the short term and in the long.

Adolescent↗
PubMedDate not supplied

Cancer prevention in the community: a survey of community residents.

Lifestyle exposures account for the greatest proportion of risk factors for cancer, yet these exposures have proven most difficult to alter. Despite intensive intervention efforts, many behaviour change programs are ill suited to the community. This research was undertaken to increase our understanding of prevention activities of interest to a sample of residents in two Ontario communities. 248 (62.3%) adult residents responded to a semi-structured self-administered questionnaire including open-ended questions on health issues, exposures and prevention activities of interest. While some of the beliefs expressed by respondents might have been anticipated (e.g., cigarette smoking and family history increase risk of cancer), others were not (e.g., only between 40 and 75% of respondents thought a high fat diet increased risk). Furthermore, many of those with personal health concerns expressed an interest in prevention. This process is proposed as a first step in launching more appropriate and sustainable community-based health promotion programs for cancer prevention.

Adult↗
PubMedDate not supplied

An investigation of two apparent cancer clusters in one community.

Two apparent cancer clusters in a single municipality were brought to public attention within a few years of each other. The clusters occurred first in a high school and later in a general hospital across the street. Analysis of the clusters was based on the comparison of the observed with the expected cancers, where the expectation of cancer occurrence was derived from data in the Ontario Cancer Registry. While the observed/expected ratios were statistically significant for the high school staff and students, these ratios were based on a very small number of cases (n = 6), and represented 4 different cancer types. The data for the hospital did not appear as excess cancer, either across age groups or in different working locations within the hospital. In addition, cancer rates were examined for the town in which the high school and hospital were located. A number of alternative explanations are discussed, as are the issues surrounding the analysis of cancer clusters in the community. We concluded that the two apparent clusters did not require further study.

Adult↗
PubMedDate not supplied

Cancer incidence in an urban community: an historical cohort study.

This historical cohort study tested the hypothesis that residents of an industrialized urban community were at higher risk of cancer than residents of a comparable, but non-industrialized, community. The exposed (C1) and the unexposed (C2) cohorts resided in their respective neighbourhoods between 1952 and 1956. All incident cancers were identified through linkage with the Ontario Cancer Registry for 1964-1982. Cancer incidence rates in the two cohorts were 7.0 and 7.3 per 1,000 person-years, respectively. Relative risk estimates for all cancers, lung cancer and cancers associated with environmental exposure, were not significantly different from 1.0. Only colorectal cancers were significantly more frequent in the C1 than the C2 cohort, and these only in one sub-analysis. Overall, we conclude that if there was increased risk of cancer related to environmental pollution in the industrially exposed community, it was less than a two-fold increase.

Adolescent↗