Viral load of human papilloma virus 16 as a determinant for development of cervical carcinoma in situ: a nested case-control study.

Background: Infection with certain types of human papillomavirus (HPV), which is common among young women, increases the risk of cervical cancer. However, less than 1% of young women positive for oncogenic types of HPV develop cervical cancer. We investigated whether the amount of HPV DNA is a useful predictor of progression to cervical carcinoma in situ.

Multiple sclerosis and poliomyelitis. A Danish historical cohort study.

Objective: To evaluate whether persons with a history of poliomyelitis are at an increased risk of developing multiple sclerosis (MS).

Material And Methods: All patients diagnosed with acute poliomyelitis in the greater capital area of Copenhagen, Denmark, between 1919 and 1954 were identified and followed with respect to MS. Information on vital status and diagnosis of sclerosis was obtained through linkage with the Danish Civil Registration System and The Danish Multiple Sclerosis Registry, respectively.

Maternal age and fetal loss: population based register linkage study.

Objective: To estimate the association between maternal age and fetal death (spontaneous abortion, ectopic pregnancy, stillbirth), taking into account a woman's reproductive history.

Design: Prospective register linkage study.

Subjects: All women with a reproductive outcome (live birth, stillbirth, spontaneous abortion leading to admission to hospital, induced abortion, ectopic pregnancy, or hydatidiform mole) in Denmark from 1978 to 1992; a total of 634 272 women and 1 221 546 pregnancy outcomes.

alpha-fetoprotein levels in maternal serum during pregnancy and maternal breast cancer incidence.

Background: A full-term pregnancy is associated with a reduced risk of breast cancer, but the underlying biologic mechanism has not been elucidated. During pregnancy, maternal serum levels of alpha-fetoprotein, an estradiol-binding protein, rise sharply. In culture, alpha-fetoprotein inhibits the growth of estrogen-sensitive cells, including estrogen-sensitive breast cancer cells.

[Should all younger patients with breast cancer be offered adjuvant cytotoxic chemotherapy?].

The aim of the study was to investigate whether young age at diagnosis is a negative prognostic factor in primary breast cancer and how stage of disease at diagnosis and treatment may influence such an association. It was conducted as a retrospective cohort study based on a population-based data-base of breast cancer diagnosis with detailed information on tumour characteristics, treatment regimens, and vital status and included 10,356 patients with primary breast cancer less than 50 years of age at diagnosis. The main outcome measures were relative risk of dying within the first ten years after diagnosis according to age at diagnosis, adjusted for effect of known prognostic factors and expected mortality.

Gender of offspring and long-term maternal breast cancer risk.

Gender of offspring is influenced by maternal hormonal level during pregnancy, which is believed to influence the subsequent maternal breast cancer risk. However, analysing national birth and cancer registrations in a cohort of 998,499 women, we found no association between gender of offspring and subsequent breast cancer risk.

Non-melanoma skin cancer may be a marker of poor prognosis in patients with non-Hodgkin's lymphoma.

According to recent results, patients with non-melanoma skin cancers are at increased risk of developing non-Hodgkin's lymphoma (NHL). The prognostic significance of this association is unknown. Two cohorts of patients with a first diagnosis of non-melanoma skin cancer and a subsequent diagnosis of either NHL (n = 170) or colon cancer (n = 435) were established using national cancer registry data in Denmark.

Factors influencing the effect of age on prognosis in breast cancer: population based study.

Objective: To investigate whether young age at diagnosis is a negative prognostic factor in primary breast cancer and how stage of disease at diagnosis and treatment influences such an association.

Design: Retrospective cohort study based on a population based database of patients with breast cancer containing detailed information on tumour characteristics, treatment regimens, and survival.

Setting: Denmark.

Salivary gland cancer in the United States.

The risk of salivary gland cancer (SGC) is increased in atomic bomb survivors and after radiotherapy, but other risk factors are not well established. Some studies have suggested an association of SGC with breast cancer and with exposure to various viruses or UVB radiation. Corroborating evidence of these associations was sought by using population-based registries to examine the demographic distribution of SGC, patterns of secondary primary cancers after SGC, and risk of SGC with AIDS.

Reproductive history and stage of breast cancer.

A woman's reproductive history influences her risk of breast cancer. The authors hypothesized that reproductive history also influences stage of disease at the time of diagnosis. The authors analyzed a population-based cohort of 1.

Is history of squamous-cell skin cancer a marker of poor prognosis in patients with cancer?

Background: Nonmelanoma skin cancer is associated with increased occurrence of subsequent cancer and death from cancer, but it is not known whether a history of skin cancer is associated with poor prognosis after a second diagnosis of cancer.

Objective: To determine whether history of squamous-cell skin cancer is a marker of poor prognosis in patients with cancer.

Design: Population-based cohort study.

Exposure to prenatal and childhood infections and the risk of schizophrenia: suggestions from a study of sibship characteristics and influenza prevalence.

Background: It has been proposed that infections, perhaps prenatal exposure to the influenza virus, might increase the risk of schizophrenia. To address this hypothesis, we studied the possible influence on schizophrenia risk of sibship characteristics and ecological influenza prevalence data. Birth order and influenza prevalence were used as proxy measures for exposure to prenatal infection, and sibship size and interval to siblings were used as proxy measures for exposure to common childhood infections.

Sex ratios, family size, and birth order.

In many countries, the male:female ratio at birth has varied significantly over the past century, but the reasons for these changes have been unclear. The authors observed a close parallel between decreasing family size and declining male:female sex ratio in Denmark from 1960 to 1994. To explain this finding, they examined the sex ratio and birth order of 1,403,021 children born to 700,030 couples.

Bowen disease and risk of subsequent malignant neoplasms: a population-based cohort study of 1147 patients.

Objective: To address the long-standing question of whether patients with Bowen disease are at increased risk of internal malignant neoplasms.

Patients: A total of 1147 Danish patients diagnosed between 1978 and 1993 as having Bowen disease at nongenital sites were followed up for 6463 person-years for cancer occurrence up to 16 years after the skin lesion.

Main Outcome Measure: Standardized incidence ratios (SIRs)--the ratios of observed-to-expected numbers of cancer--served as measures of relative risk.

Preterm delivery and risk of breast cancer.

To explore the risk of breast cancer in relation to the length of a pregnancy we tested whether a preterm delivery carries a higher risk of breast cancer than does a full-term delivery. Based on information from the Civil Registration System, and the National Birth Registry in Denmark, we established a population-based cohort of 474 156 women born since April 1935, with vital status and detailed parity information, including the gestational age of liveborn children and stillbirths. Information on spontaneous and induced abortions was obtained from the National Hospital Discharge Registry and the National Registry of Induced Abortions.

Maternal risk of breast cancer and birth characteristics of offspring by time since birth.

We examined the association between birth characteristics of offspring and the subsequent maternal risk of breast cancer in a population-based cohort of 998,499 women, 13 to 48 years of age at entry. There were 9,495 incident cases of breast cancer during 12.8 million person-years of follow-up among these women.

Multivariate competing risks.

Competing risks models can be used to compare the effect of risk factors for different causes of death or subtypes of a disease. However, sometimes more than one outcome classification is available and if two such classifications are correlated, one may speculate whether differences in the effect of a risk factor according to one classification simply may be an effect of differences according to the other correlated classification. We introduce in this paper the new concept of multivariate competing risks to test formally such a hypothesis.

Epstein-Barr virus and cytomegalovirus in relation to testicular-cancer risk: a nested case-control study.

An infectious etiology of testicular cancer has been suggested. We have evaluated seroreactivity against cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in relation to testicular-cancer risk in a case-control study, nested within a cohort of prospectively collected serum specimens from 293,692 individuals. For each of 81 cases of testicular cancer identified, 3 controls were randomly selected from the cohort.

Tobacco smoking as a risk factor in anal carcinoma: an antiestrogenic mechanism?

Background: Human papillomavirus-associated anogenital carcinogenesis depends on poorly defined cofactors. Smoking was recently suggested to increase the risk of anal cancer more in premenopausal women than in postmenopausal women. Thus, we used our population-based anal cancer case-control study in Denmark and Sweden to test this hypothesis.

Smoking and oral contraceptives as risk factors for cervical carcinoma in situ.

Human papillomavirus (HPV) is probably a necessary but definitely not a sufficient cause of cervical carcinoma. However, it remains unclear which factors, in addition to HPV, are important for the development of cervical carcinoma and its precursor lesions. To address this issue, we conducted a case-control study nested in a population-based cohort consisting of women participating in cytological screening in one Swedish county, any time during 1969 through 1995.

Risk factors for parvovirus B19 infection in pregnancy.

Context: Parvovirus B19 infection during pregnancy has been associated with fetal death. However, the incidence of and risk factors for infection in pregnant women have not been well studied.

Objectives: To estimate a pregnant woman's risk of infection with parvovirus B19 in epidemic and endemic situations and to study risk factors for infection.

Respiratory tract infections in Greenlandic children: a prospective cohort study.

Respiratory tract infections in children, measured in terms of both morbidity and mortality, represent a major health problem in Greenland. In particular, otitis media is highly prevalent, and is characterized by early onset and a high degree of chronicity. There is, however, little knowledge about the epidemiology of respiratory tract infections in Greenland.