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I Heuch

Publications and source records attributed to I Heuch.

At least 37 records · Page 2Linked to original sources
PubMed1995

Is the risk of cancer of the corpus uteri reduced by a recent pregnancy? A prospective study of 765,756 Norwegian women.

We have examined the relations between the incidence of cancer of the corpus uteri and pregnancies in a cohort of 765,756 Norwegian women, contributing a total of 9,307,118 person-years in the age interval 30-56 years. Incidence rate ratios (IRR) were calculated by Poisson regression analyses of person-years at risk. Separate analyses were carried out for the 2 main histological subtypes, endometrial carcinomas (554 cases) and sarcomas (112 cases). We observed a decrease in risk of endometrial carcinoma with an increasing number of full-term pregnancies (p < 0.001). The reduction in risk associated with the first pregnancy was more pronounced than that observed for any subsequent pregnancy. The risk of endometrial carcinoma increased with increasing time since last birth (IRR = 1.20, 95% CI = 1.08-1.34 per 5-year time interval). The reduction in risk among parous women compared to nulliparous women diminished with increasing time since last birth. For endometrial carcinoma, the decrease in risk with increasing age at first and last birth disappeared after adjustment for time since last birth. For sarcomas, however, the relation with age at births remained in analyses adjusted for time since birth, and time since birth seemed to be of minor importance as an independent risk factor. Our results support the hypothesis that the reduction in risk of endometrial carcinoma associated with a pregnancy is related to a mechanical shed of malignant or pre-malignant cells at each delivery.

Adult↗
PubMed1995

Multiple births, sex of children and subsequent breast-cancer risk for the mothers: a prospective study in Norway.

Endocrinological changes occurring during pregnancy may influence the subsequent cancer risk of the mother. Further, the endocrinological milieu may differ according to different birth characteristics. In the present study possible relations between multiple births, sex of children and breast-cancer risk were examined in a population-based, prospective study of 802,269 parous Norwegian women aged 20-56 years. A total of 4,782 women were diagnosed with breast cancer during follow-up. Of these, 97 had ever experienced a multiple birth. We found a slightly lower risk of breast cancer among women ever having had a multiple birth than among women with singletons only (IRR = 0.89, 95% CI = 0.73-1.09). The reduction in risk was mainly observed among women with a multiple last birth. Further, the reduction in risk seemed to diminish with increasing parity, and among women with 4 or more full-term pregnancies, ever having had a multiple birth was associated with an elevated risk (IRR = 1.48, 95% CI = 0.97-2.25). The sex of the first or last child did not affect the subsequent breast-cancer risk. Further, we found no associations with the sex distribution among all children or in multiple births, despite a tendency toward a reduced risk among women with several daughters only.

Adult↗
PubMed1995

The short-term and long-term effect of a pregnancy on breast cancer risk: a prospective study of 802,457 parous Norwegian women.

Time-related effects of a pregnancy on breast cancer risk were examined in a population-based prospective study of 802,457 parous Norwegian women aged 20-56 years. The mean follow-up time was 16.4 years. A total of 4787 women were diagnosed with breast cancer. We observed a short-term increase in risk of breast cancer after a full-term pregnancy, with a maximum 3-4 years after delivery, followed by a long-lasting decrease in risk. The maximum risk was about twice the risk for women whose last delivery was 20 or more years previously (incidence rate ratio = 1.99, 95% confidence interval = 1.70-2.33). Compared with nulliparous women, those with one or two children were at higher risk in the first decade after the last pregnancy, whereas those with three or more children were at lower risk in most categories of time since the last birth. The positive association between breast cancer risk and age at last birth was markedly reduced after adjustment for time since last birth. We conclude that there is a non-linear relationship between breast cancer incidence and time since last birth. Part of the relation with age at last birth may be attributed to the association with time since last birth.

Adult↗
PubMed1994

Parity in relation to mortality and cancer incidence: a prospective study of Norwegian women.

BACKGROUND: Few prospective studies relating childbearing to total and cause-specific mortality and cancer incidence have been published. The purpose of this paper was to examine these relations in a large cohort of Norwegian women. METHODS: Information on reproductive factors was obtained through interviews with 63,090 women. All deaths and cancer cases during follow-up, 1961-1980, were obtained by linkage to the files at the Central Bureau of Statistics and the Cancer Registry of Norway, respectively. Associations with parity were assessed by stratified logistic regression. RESULTS: For cerebrovascular and ischaemic heart disease, moderate but highly significant positive trends of increasing mortality with increasing parity were observed in the older part of the cohort. Deaths from diseases of the respiratory system and suicide were most common among nulliparous women. Inverse associations with parity were observed for cancers of the breast, corpus uteri and ovaries as well as for melanoma and non-melanoma skin cancers. Positive associations were observed for cancer of the cervix uteri in all age groups, for cancer of the respiratory system among older women and for pancreatic cancer and multiple myelomas in the younger part of the cohort. The results gave no support to previous reports of positive associations with cancer of the liver or gallbladder. CONCLUSIONS: The study supports evidence of an increased risk of ischaemic heart disease in multiparous women, which had been observed previously in three smaller prospective studies. It confirms earlier observations of low risks of cancer of the breast, corpus uteri and ovaries in women with high parity.

Adult↗
PubMed1994

Breast cancer incidence before age 55 in relation to parity and age at first and last births: a prospective study of one million Norwegian women.

We examined the relation between breast cancer, parity, and age at first and last births in a large national cohort of young women in Norway. We estimated relative incidence rates by Poisson regression analyses of person-years at risk with parity and age at last (most recent) birth as time-dependent variables. A total of 1,071,795 women were included in follow-up, contributing a total of 16,643,883 person-years in the age range 20-54 years. Follow-up times ranged from 1 month to 34.5 years. A total of 4,302 women were diagnosed with breast cancer during follow-up. With adjustment for age at first and last births, high parity was associated with an overall reduced risk of breast cancer (incidence rate ratio = 0.46; 95% confidence interval = 0.36-0.59 for women with five or more children vs uniparous women). Among women age 20-29 years, however, the results suggested an increase in risk with increasing parity (incidence rate ratio = 1.25; 95% confidence interval = 0.64-2.45 for women with three children vs uniparous women). The protective effect of high parity was particularly strong among women with first birth before the age of 20 years and rather weak among those with first birth at age 30 years or more. Low ages at first and last births were both associated with reduced breast cancer risk in analyses with adjustment for the other factor, with the association with age at last birth being slightly stronger.

Adult↗
PubMed1994

Maximum likelihood estimation of the proportion of congenital malformations using double registration systems.

Since 1970, epidemiological surveillance of congenital malformations has been carried out in Norway on the basis of data in the nationwide Medical Birth Registry. A separate local registry of cases occurring in the county of Hordaland was established in 1985 to clarify problems inherent in the reporting. This paper deals with double sampling estimators of the prevalence at birth of various malformations, utilizing joint data from two such registries. Particular examples include Down's syndrome, malformations of the central nervous system (CNS), cleft lip or cleft palate, and hypospadias. The methods applied also allow estimation of the probabilities of ascertainment of the different malformations in each registry. Expressions are derived for the variances of the asymptotic distributions of the double sampling estimators, and the possibility of using these values to detect true changes in disease prevalence when ascertainment is uncertain is discussed. The merits of double sampling are assessed comparing the crude estimator based on the Medical Birth Registry alone with the double sampling estimators. Finally, some fully parameterized alternatives to the double sampling models are introduced to evaluate some of the assumptions involved.

Biometry↗
PubMed1993

A new sequential procedure for surveillance of Down's syndrome.

A new method is proposed for the surveillance of Down's syndrome among newborn. Despite the strong dependence of overall risk of Down's syndrome on maternal age, it has been suggested that an environmentally induced increase in risk may be additive over all maternal ages. The surveillance method introduced here is specifically designed to detect such changes. The method is based on registry data for successive periods for a given population. It is assumed that the number of Down's syndrome cases as well as the total number of births are known in all maternal age groups. Tables of average run lengths until an alarm (ARLs) are calculated for a total sample size of 14,500 in each period, the approximate number of births in a three-month period in Norway. Comparison with the Poisson cusum shows that the new surveillance method can detect moderate additive increases significantly faster. Applied retrospectively to quarterly data from the Medical Birth Registry of Norway for 1978-89, the proposed method was close to an alarm in 1985 and actually signalled a strong alarm in 1986, reflecting a previously reported increase in risk in this period. The cusum method was not so sensitive to the aberration in Down's syndrome risks in 1985 and 1986.

Adult↗
PubMed1991

Is the incidence of colorectal cancer related to reproduction? A prospective study of 63,000 women.

Relationships between reproductive factors and risk of colorectal cancer were examined in a population-based prospective study in Norway. Available for analysis were 831 cases (581 colon cancer, 250 rectal cancer) diagnosed in a cohort of 63,090 women, surveyed in 1956-1959 and followed through 1980. Overall, the analyses showed no strong effects of reproductive factors. In particular, high parity was not associated with reduced risk, and late age at first or last birth was not associated with an increased overall risk. However, in age-specific analyses of colon cancer, adverse effects of late age at first birth and late age at last birth were observed in women with cancer diagnosed before the age of 60. A non-significant overall excess risk in parous compared to nulliparous women was strongest for women with a cancer diagnosis before the age of 50 years. Having had many abortions was associated with increased risk for all sub-sites. Neither age at menarche nor age at menopause were related to risk of colorectal cancer. The results suggest that reproductive factors, which are of importance in the etiology of cancer of the breast and genital organs in women, are not similarly related to risk of colorectal cancer.

Abortion, Spontaneous↗
PubMed1991

A temporary increase of Down syndrome among births of young mothers in Norway: an effect of risk unrelated to maternal age?

The Medical Birth Registry of Norway carries out a population-based surveillance of birth defects on a routine basis. An increased proportion of newborn with Down syndrome was seen among children of young mothers during 1985-1986. Three alternative explanations were considered: a first representing a maternal age specific effect, a second based on a general increase in a subgroup of cases caused by factors not related to maternal age, and a third based on the assumption that a particular birth cohort of young women was carrying a high risk. As 1987 and 1988 showed very low proportions in all age groups, the last explanation was considered less likely. Statistical modeling was used to explore which of the two remaining explanations of the temporary increase was the more likely. The observed changes were compatible with a change in the occurrence of a group of maternal age-independent Down syndrome cases, from 4.59 per 10,000 in 1973-1984 and again in 1987-1988 to a temporary high of 7.68 per 10,000 in 1985-1986. However, the possibility of an age specific change only among young mothers could not be ruled out.

Adolescent↗
PubMed1991

Reproductive factors and cancers of the breast and genital organs--are the different cancer sites similarly affected?

Relationships between reproductive factors and cancer of the breast and genital organs were investigated in a prospective study of 63,090 Norwegian women. During followup from 1961 through 1980 1565 cases of breast cancer, 422 cases of cancer of the corpus uteri, and 471 cases of ovarian cancer were diagnosed. High parity was associated with low risk of cancer of the breast, corpus uteri, and ovary in analyses with adjustment for age at first birth. Age at first birth and age at last birth were positively associated with risk of breast cancer and inversely associated with endometrial cancer, whereas no clear associations were observed with ovarian cancer. Results suggest that the effect of a pregnancy on cancer risk is mediated, at least in part, by different mechanisms for these three sites. Age at menarche was inversely and age at menopause positively related to risk of breast and endometrial cancer, whereas no association was observed for ovarian cancer. In analyses of squamous cell carcinoma of the cervix uteri, an association with reproductive factors was expected from the known relationships with sexual habits. However, this cannot account for the high risk observed in this study in women with early age at first birth.

Abortion, Spontaneous↗
PubMed1990

Milk consumption and cancer incidence: a Norwegian prospective study.

Relationships between milk intake and cancer incidence were investigated after 11 1/2 years of follow-up of 15,914 individuals. A diagnosis of cancer was made in a total of 1,422 individuals. No association was established with total cancer incidence, in analyses adjusted for sex, age and residential characteristics. However, a strong positive association with milk consumption was observed for cancers of the lymphatic organs (odds ratio 3.4 for greater than or equal to 2 glasses per day vs less than 1; 95% confidence interval 1.4-8.2). An inverse association was found for cancer of the bladder. Kidney cancer and cancers of the female reproductive organs (except the uterine cervix) showed weak positive associations with milk intake.

Adult↗
PubMed1988

Reproductive factors and risk of cancer of the uterine corpus: a prospective study.

Relationships between reproductive factors and risk of cancer of the uterine corpus were investigated in a prospective study of 62,079 women in Norway. A total of 420 cases were diagnosed during follow-up, from 1961 through 1980. The risk of endometrial carcinoma decreased significantly with increasing parity as well as with increasing age at first and last birth. The estimated odds ratio for women with 5 or more births versus uniparous was 0.60 in analyses with adjustment for age and residence characteristics. For first birth at age greater than or equal to 35 versus less than or equal to 19 the odds ratio was 0.48, and for last birth at age greater than or equal to 40 versus less than or equal to 24 we found an odds ratio of 0.45, in analyses with additional adjustment for parity. Significant associations were also found with age at menarche and menopause, the highest risks being observed for women with early menarche or late menopause. The different reproductive variables seemed to affect the risk of sarcomas of the uterine corpus and the risk of endometrial carcinomas in a similar way.

Adult↗
PubMed1988

Menstrual factors and breast cancer risk.

Relationships between menstrual factors and breast cancer risk were investigated in a prospective study of 63,090 Norwegian women. A total of 1565 cases of breast cancer occurred during follow-up from 1961 through 1980. The risk of breast cancer decreased with increasing age at menarche (P = 0.06) and increased with increasing age at menopause (P = 0.005) in analyses adjusted for age, urban/rural place of residence, parity, and age at first and last birth. The results correspond to an average increase in breast cancer risk of 4.0% for each year of decrease in age at menarche, and an increase in risk of 3.6% for each year of increase in age at menopause. The protective effect of early menopause was strongest for breast cancer diagnosed in patients 80 years of age or older. No clear relationship was seen between menstrual irregularities and breast cancer risk.

Adult↗