[Hormone replacement therapy in Iceland.].

Objective: The aim of this study was to investigate the use of hormone replacement therapy (HRT) in Iceland in 1979-1995.

Material And Methods: The data used were based on answers to a questionnaire for women who attended screening for cervical and breast cancer at the Cancer Detection Clinic of the Icelandic Cancer Society. More than 95% of all Icelandic women in the age groups investigated attended screening during the period and participated in the study.

BRCA2 mutation in Icelandic prostate cancer patients.

Molecular genetic analysis of prostate cancer has gained considerable attention in recent years. The hope is to find genetic markers that can help to determine which patients are likely to develop a progressive or lethal disease and would therefore benefit from early treatment. The BRCA2 gene on chromosome 13 has been associated with familial male and female breast cancer.

Risk factors for malignant diseases: a cohort study on a population of 22,946 Icelanders.

The records of a cohort of 11,580 females and 11,366 males participating in an Icelandic cardiovascular risk factor study were linked with the Icelandic Cancer Registry, identifying 1,785 males and 1,490 females who had been registered with neoplastic diseases from 1968 to 1995. The interval between the time of measurement of the variables and the diagnosis of the malignancy ranged from 4 to 27 years. The variables consisted of answers from a questionnaire on smoking and the use of hypertensive drugs and anthropometric and biochemical measurements.

Study of a single BRCA2 mutation with high carrier frequency in a small population.

Germ-line changes in the cancer-predisposition gene BRCA2 are found in a small proportion of breast cancers. Mutations in the BRCA2 gene have been studied mainly in families with high risk of breast cancer in females, and male breast cancer also has been associated with BRCA2 mutations. The importance of germ-line BRCA2 mutations in individuals without a family history of breast cancer is unknown.

Genomic instability and poor prognosis associated with abnormal TP53 in breast carcinomas. Molecular and immunohistochemical analysis.

Alterations of the TP53 gene were analyzed in samples from 87 primary breast cancer patients, using molecular and immunohistochemical approaches. Mutations were detected in 17% of the samples, using polymerase chain reaction (PCR) and constant denaturant gel electrophoresis (CDGE) on exons 5-8 of the TP53 gene, and were confirmed by sequencing. Abnormal TP53 protein staining was found in 55% of the primary samples, using the monoclonal TP53 antibody DO7.

Summary of avoidable cancers in the Nordic countries.

An overview is given of the most important known causes of cancer in the five Nordic countries and the resulting number of cancers that are potentially avoidable. The main causes include active and passive smoking, alcohol consumption, exposure to asbestos and other occupational carcinogens, solar and ionizing radiation, obesity, human papillomavirus infection in the female genital tract and infection with Helicobacter pylori. The organs most commonly affected are those of the respiratory system, the upper digestive tract and stomach, skin, the lower urinary tract and the uterine cervix.

Avoidable cancers in the Nordic countries. Exogenous hormones.

The well-described influence of several aspects of reproductive life on the risk for cancer in the reproductive organs has raised concern regarding the safety of exogenous hormones, particularly since sex hormones have become one of the most widely used drugs among women in the western world. The major areas of application include oral contraception and hormone replacement therapy in women with menopausal symptoms. Since the introduction of oral contraceptives onto the Nordic market in the late 1960s, the number of users has grown steadily, to reach proportions of long-term users among women aged 15-45 years in 1985 ranging between 6% (Norway) and 19% (Sweden) and proportions of current users in 1994 ranging between 20% (Norway) and 28% (Sweden).

Avoidable cancers in the Nordic countries. Biological agents.

Although several biological agents have been linked convincingly with increased risks for cancer in humans, only infection of the lower female genital tract with human papillomavirus (HPV) and colonization of the gastrointestinal tract with Helicobacter pylori are of importance for cancer occurrence in the Nordic countries. HPV types 16 and 18, and probably types 31 and 33, are causally linked with cervical cancer and H. pylori, a Gram-negative bacteria, with gastric cancer.

Oral contraceptive use at a young age and the risk of breast cancer: an Icelandic, population-based cohort study of the effect of birth year.

The possible association between breast cancer and oral contraceptive use before the age of 20 was investigated using Icelandic population-based information from women born after 1944. The design was a nested case-control study within a cohort, using data on duration of oral contraceptive use at young ages. The availability of oral contraceptives before the age of 20 has changed dramatically and is highly dependent on birth years, with 20% and 82% starting before the age of 20 among Icelandic users born in 1945-47 and 1963-67 respectively.

TP53 mutation analyses on breast carcinomas: a study of paraffin-embedded archival material.

The aim of this investigation was to examine the possibility of analysing TP53 mutations in archival paraffin-embedded material with the constant denaturant gel electrophoresis (CDGE) method. We extracted DNA from 193 archival primary breast carcinoma samples, diagnosed in 1981-83; further analysis was possible for 186 of these. TP53 mutations in exons 5-8 were detected with CDGE in 30 samples (16.

[The pattern of use of oral contraceptives in Iceland 1965 to 1989.].

Introduction: Around 20% of Icelandic women of childbearing age use oral contraceptives. Knowledge of the health effects of oral contraceptive use and patterns of use is of importance. Patterns of use were studied, according to birth cohorts and age for the years 1965 to 1989.

A single BRCA2 mutation in male and female breast cancer families from Iceland with varied cancer phenotypes.

The BRCA2 gene on chromosome 13 has been shown to be associated with familial male and female breast cancer. Here we describe a study on BRCA2 in 21 Icelandic families, including 9 with male breast cancer. We have previously reported linkage to the BRCA2 region in an Icelandic male breast cancer family and subsequently found a strong indication of linkage to BRCA2 and the same BRCA2 haplotype in breast cancer cases from 15 additional families, indicating a common origin.

TP53 mutations and abnormal p53 protein staining in breast carcinomas related to prognosis.

Abnormalities in the TP53 tumour suppressor gene were evaluated in 106 unselected breast carcinomas and compared to clinical outcome of the disease. Tumours were screened for p53 abnormalities using immunohistochemical staining and polymerase chain reaction-constant denaturant gel electrophoresis (PCR-CDGE) analysis, followed by PCR and direct sequencing. Allelic loss at the TP53 locus was determined with polymorphic markers by comparing normal and tumour DNA.

Linkage to BRCA2 region in hereditary male breast cancer.

Breast cancer is rare in men, and family history of the disease is a risk factor. The recently discovered BRCA2 gene on chromosome 13q is thought to account for some families with increased risk of breast cancer, including male breast cancer. We describe a family with multiple cases of male breast cancer but, interestingly, no increase in female breast cancer.

Neoplastic diseases in families of breast cancer patients.

Objective: To investigate whether the risk of cancer at all sites, and at individual sites other than breast, prostate, ovaries, and endometrium, is increased among relatives of breast cancer patients compared with the general population.

Design: A cohort of family members of breast cancer patients was established. The probands were chosen by year of birth or time of diagnosis.

A decline and a halt in mean age at menarche in Iceland.

Mean age at menarche has been declining in many countries during the past hundred years. Reports of a halt in this trend have come from Oslo and London. In this study the trend in age at menarche in successive birth cohorts, starting in 1900, was investigated for the first time in Iceland.

Epidemiology of breast cancer in families in Iceland.

The Icelandic Cancer Registry has collected 989 pedigrees of breast cancer patients since 1972. In addition to the probands, the families also include 401 other women with breast cancer, so family information exists for 1390 women with breast cancer out of a total of 2748 diagnosed with the disease from 1910 to 1988. Most of the probands have been selected with care to avoid the bias of selecting families with a known history of breast cancer.

Reproductive factors and breast cancer risk in Iceland. A second cohort study.

In a previous prospective study we showed elevated risks for breast cancer in nulliparous women compared to parous women, in those having their first pregnancy at a higher age, and those with few children. This was based on 216 women diagnosed with breast cancer during 1965 to 1975 among 34,525 women having attended the cervix cancer detection clinic in Iceland by the end of 1974, and born between 1906 and 1945. The present investigation on 848 cases, diagnosed among 61,040 women attending the cervix cancer detection clinic during 1964 to 1984 and born between 1901 and 1960, shows the same risk factors to be significant.

Familial and sporadic breast cancer cases in Iceland: a comparison related to ABO blood groups and risk of bilateral breast cancer.

This study was aimed at determining whether the familial clustering often observed in breast cancer is associated with genetic factors. We compared familial and sporadic breast cancer cases with respect to ABO blood group distribution and the risk of bilateral disease, using the data from the Icelandic Cancer Registry which contains genealogical information for about 30% of the breast cancer cases diagnosed in Iceland since 1911. Cases were classified as familial if at least one first-degree relative had breast cancer.