The Tromsø Mammography and Breast Cancer Study

The Tromsø Mammography and Breast Cancer Study

Breast cancer is the most commonly occurring malignancy among Norwegian women. The incidence of breast cancer varies a lot around the world. This variation is an indicator that breast cancer is a preventable disease, and that lifestyle and environment factors affect the risk of breast cancer.

How a breast appears on an x-ray image (mammogram) varies by how much fatty tissue, connective tissue, and epithelial tissue there is in the breast. Epithelial and connective breast tissues are radiodense and will appear light on a mammogram, while fatty breast tissue is radiolucent and will appear dark. A mammogram can be classified according to parenchymal patterns (the original method) and percent mammographic density (the newer method).

Mammographic density – a strong risk factor for breast cancer
Epidemiological studies have shown that mammographic parenchymal patterns and mammographic density are independent risk factors for breast cancer. Apart from age and some genetic mutations, mammographic density is regarded as one of the strongest breast cancer risk factors.


We wish to study the associations between lifestyle factors, diet, hormonal therapy, endogenous hormones, genetics, biological markers and mammographic parenchymal patterns / mammographic density.

Data collection

In 2001 the Tromsø Mammography and Breast Cancer (TMBC) study was initiated at the Institute of Community Medicine, University of Tromsø. Postmenopausal women, age 55 and over, residing in the municipality of Tromsø, Norway, and attending the population-based Norwegian Breast Cancer Screening Program (NBCSP) at the University Hospital of North Norway (UNN) were eligible for the study. During spring of 2001 and 2002, altogether 1,041 women were included in the TMBC study. After the women had undergone their NBCSP screening mammograms, they were interviewed by a nurse from the Department of Clinical Research, UNN, about reproductive and menstrual factors, previous history of cancer, smoking status, and use of HT or other medications. The participants had their height and weight measured, blood samples drawn, and each was given a questionnaire to be completed at home, and returned in a prepaid envelope.

Study group

Principal Investigator
Professor Inger Torhild Gram

Institute for Community Medicine,
UiT The Arctic University of Norway
9037 Tromsø.
Telephone:  92401177 

Professor Vessela N. Kristensen
Oslo University Hospital 
Department of Cancer Genetics
Institute for Cancer Research,

Research technologist Grethe I. Grenaker Alnæs
Oslo University Hospital
Department of Cancer Genetics
Institute for Cancer Research,

Systems Analyst Ilene Brill
Department of Epidemiology and International Health,
Ryals School of Public Health,
University of Alabama at Birmingham
Birmingham, AL 35294-0022, USA.

Professor Gertraud Maskarinec
University of Hawaii, Cancer Center
Honolulu, HI 96813, USA.


The TMBC study is approved by the Regional Committee for Medical Research Ethics and the National Data Inspection Board. All women have signed an informed consent. All data are stored and handled according to the permission given by the National Data Inspection Board.

Financial support

The Norwegian Research Council

The Norwegian Women’s Public Health Association

Pink Ribbon / The Norwegian Cancer Society

The National Cancer Institute (Grant R03CA105948)

The Northern Norway Regional Health Authority

Health and Rehabilitation

The Erna and Olav Aakre Foundation

The Rikke and Conrad Holmboes Research Fund

The Odd Fellow Medical-Scientific Research Fund

The University of Tromsø


Stone J, Thompson DJ, Dos SS, I, Scott C, Tamimi RM, Lindstrom S, et al. Novel Associations between Common Breast Cancer Susceptibility Variants and Risk-Predicting Mammographic Density Measures. Cancer Res 2015 Jun 15;75(12):2457-67

Genotypes and haplotypes in the insulin-like growth factors, their receptors and binding proteins in relation to plasma metabolic levels and mammographic density. PMID: 20302654

Breast cancer screening programme as setting for an adjunct research project: effect on programme attendance., J Med Scren 2008;15:44-45

Common genetic variation in GATA-binding protein 3 and differential susceptibility to breast cancer by estrogen receptor alpha tumor status PMID: 18006915

Different measures of smoking exposure and mammographic density in postmenopausal Norwegian women: a cross-sectional PMID: 17963507

Common genetic variation in TP53 and its flanking genes, WDR79 and ATP1B2, and susceptibility to breast cancer. PMID: 176583073

Endogenous sex hormones, prolactin and mammographic density in postmenopausal Norwegian women. PMID: 17657735

IGF-I and mammographic density in four geographic locations. A pooled analysis PMID: 17520679

Mutations and polymorphisms of the p21B transcript in breast cancer PMID: 17443496

Insulin-like growth factor and mammographic density in postmenopausal Norwegian women PMID: 17220332

Different types of postmenopausal hormone therapy and mammographic density in Norwegian women PMID: 17131324

Meta- and Pooled Analyses of the Cytochrome P-4501B1 Val432Leu Polymorphism and Breast Cancer: A HuGE-GSEC Review PMID: 17053044

Ethnic and geographic differences in mammographic density and their association with breast cancer incidence PMID: 17009106

The novel p21 polymorphism p21 G251A Is Associated with Locally Advanced Breast Cancer PMID: 17062672

Plasma levels of leptin and mammographic density among postmenopusal women: a cross-sectional study PMID: 17010200

Plasma levels of enterolacton and percentage mammographic density among postmenopausal women PMID: 16172225

Percentage density, Wolfe's a.nd Tabar's mammographic patterns: agreement and association with risk factors for breast cancer PMID: 16168132

PhD thesis/Doctoral thesis

Anne Stuedal, Oslo. ISMN 978-82-8072-281-2. The role of selected nutritional and hormonal factors on mammographic density, a breast cancer risk factor

Yngve Bremnes, Tromsø. ISBM 82-90263-05-8. Hormones, smoking and Mammographic Density in Postmenopausal Norwegian women

Ansvarlig for siden: Gram, Inger Torhild
Sist oppdatert: 19.05.2020 14:13