Research in BreastScreen Norway

Research projects in BreastScreen Norway cover a wide range of topics. The overall aim is to increase our knowledge about mammographic screening and improve the screening programme.
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A number of research projects are ongoing in BreastScreen Norway. You can read more about some of these below. You can also read about a questionnaire, Q-2006, in which over 600,000 women attending BreastScreen Norway participated.

Artificial intelligence in mammographic screening

In recent years, studies have shown promising results for the use of artificial intelligence (AI) in mammographic screening, for example as a tool to support the radiologists in their assessment of mammograms. In BreastScreen Norway, a number of studies are underway to explore how this technology can be used, the advantages and disadvantages of using it, and how AI could be implemented in the screening programme in a safe and effective way.

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The future screening program

Can BreastScreen Norway be improved by offering personalized screening, so-called stratified or risk-based screening? Such a screening program could for example offer screening to certain groups of women more or less frequently than the standard two-year interval, based on their risk of developing breast cancer. We explore various factors, including the importance of mammographic density, new screening techniques such as tomosynthesis, and new opportunities that may follow the use of machine learning and AI.

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Slow growing breast cancer and overdiagnosis

How many slow growing breast cancers – often called overdiagnosed or overtreated cancers – are detected through BreastScreen Norway? Which methods are most suitable for estimating this? Can we obtain more accurate estimates of overdiagnosis than those available today? How does breast cancer progress without treatment? How does ductal carcinoma in situ progress? How does this relate to slow-growing invasive cancers and breast cancer overtreatment? Much of the research about biological development of DCIS and invasive breast cancer occurs through cooperation with the Oslo Breast Cancer Research Consortium (OSBREAC) and BreastScreen Norway’s specialist group for pathology.

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Quality of life and long-term effects of breast cancer treatment

How is women’s quality of life after being diagnosed with and treated for screen-detected breast cancer? Do these women experience different long-term effects from their treatment compared to women diagnosed with symptomatic breast cancer?

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Breast compression, pain and discomfort

How much pain and discomfort do women experience when attending mammographic screening? Can certain factors affect how women experience of pain and discomfort? What is the optimal amount of compression to apply during a screening exam?

Mammographic screening, breast cancer, and sociodemographic factors

Sociodemographic factors affect women’s participation in mammographic screening. Studies have shown that immigrant women have lower attendance at BreastScreen Norway than non-immigrant women do, and that attendance varies within immigrant populations. Are there also differences in the types of breast cancer tumours detected among immigrant and non-immigrant women through screening? If so, how does this affect their prognosis? Further, what perspectives do immigrant women have about breast cancer and BreastScreen Norway? What kind of information do they need?

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Other ongoing project with approval from Regional Committees for Medical and Health Research Ethics (REK)

Effects of the COVID-19 pandemic on the screening programs in the Netherlands and Norway, REK numer 478240

Q-2006: An epidemiological questionnaire

From August 1, 2006 to December 31, 2015, women invited to BreastScreen Norway were sent an epidemiological questionnaire togehter with their invitation to screening.

The questionnaire consisted of two parts: Part 1, Health conditions before the age of 50, and Part 2, Present health conditions. Part 1 was answered once by each woman. The questions in this part dealt with demographic variables and other health indicators that are generally constant. These included country of birth, age at first birth, number of births, breastfeeding, age at menopause, physical activity and other lifestyle factors before age 50.

Part 2, Present health conditions, asked women about conditions that change over time and was sent with each invitation. This questionnaire asked about weight, height, use of hormones, menstrual status, physical activity and other lifestyle factors.

An information sheet about the questionnaire was included with the invitation.

Over 600,000 women submitted one or more questionnaires. Overall, about 1,700,000 questionnaires were submitted. Just under 400,000 women submitted Part 1 of the questionnaire and just over 500,000 submitted Part 2 at least one time.

The validity of certain questions was analyzed in 2018. Sensitivity, specificity and positive predictive value (PPV) were calculated for self-reported screening history, and previous diagnoses of breast cancer (1). The sensitivity and specificity for self-reported breast cancer history were both > 96%, and the sensitivity and PPV for screening history were 99% and 97%, respectively. The reliability of self-reported weight and height was analyzed for women who had answered these questions twice. Both variables showed good reliability, with a difference of 1 kg and 1 cm in the two reports, respectively.

The questionnaire data contains a lot of useful information about women's health over a 10-year period. Weight and height can be used to calculate BMI, which is very important to consider in relation to mammographic density.

Scientific publications using data from the questionnaires include:

  1. Tsuruda KM, Sagstad S, Sebuodegard S, Hofvind S. Validity and reliability of self-reported health indicators among women attending organized mammographic screening. Scand J Public Health. 2018;46(7):744-51.
  2. Ellingjord-Dale M et al. Alcohol, Physical Activity, Smoking, and Breast Cancer Subtypes in a Large, Nested Case-Control Study from the Norwegian Breast Cancer Screening Program. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2017;26(12):1736-44.
  3. Ellingjord-Dale M et al. Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program. Breast cancer research : BCR. 2017;19(1):10.
  4. Ellingjord-Dale M et al. Number of Risky Lifestyle Behaviors and Breast Cancer Risk. JNCI cancer spectrum. 2018;2(3):pky030.
  5. Hjerkind KV et al. Volumetric Mammographic Density, Age-Related Decline, and Breast Cancer Risk Factors in a National Breast Cancer Screening Program. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2018;27(9):1065-74.
  6. Moshina N et al. Automated Volumetric Analysis of Mammographic Density in a Screening Setting: Worse Outcomes for Women with Dense Breasts. Radiology. 2018;288(2):343-52.
  7. Moshina N et al. The impact of compression force and pressure at prevalent screening on subsequent re-attendance in a national screening program. Prev Med. 2018;108:129-36.
  8. Moshina N, Sebuodegard S, Hofvind S. Is breast compression associated with breast cancer detection and other early performance measures in a population-based breast cancer screening program? Breast Cancer Res Treat. 2017;163(3):605-13.
  9. Moshina N et al. Breast compression parameters and mammographic density in the Norwegian Breast Cancer Screening Programme. Eur Radiol. 2018;28(4):1662-72.
  10. Holen A et al. Screening at stationary versus mobile units in BreastScreen Norway. Journal of medical screening. 2020;27(1):31-9.
  11. Larsen M, Moshina N, Sagstad S, Hofvind S. Factors associated with attendance and attendance patterns in a population-based mammographic screening program. Journal of medical screening. 2020;In press.
  12. Bjelland EK, Hofvind S, Byberg L, Eskild A. The relation of age at menarche with age at natural menopause: a population study of 336 788 women in Norway. Human reproduction (Oxford, England). 2018;33(6):1149-57.
  13. Gottschalk MS et al. Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway. Human reproduction (Oxford, England). 2020;35(2):464-71.
  14. Bjelland EK, Gran JM, Hofvind S, Eskild A. The association of birthweight with age at natural menopause: a population study of women in Norway. International journal of epidemiology. 2019.
  15. Sandvei MS et al. Menopausal hormone therapy and breast cancer risk: effect modification by body mass through life. European journal of epidemiology. 2019;34(3):267-78.