Under- and Overdiagnosis in BreastScreen Norway

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Total Enrollment

3915 participants

Study Classification

OBSERVATIONAL

Study Start Date

2018-07-01

Study Completion Date

2020-06-08

Brief Summary

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This PhD project will describe tumour characteristics and survival associated with of under- and overdiagnosed breast cancers, the rate of overdiagnosis in BreastScreen Norway, and whether women and family doctors are aware of, and knowledgeable about, under- and overdiagnosis in breast cancer screening.

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Detailed Description

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Mammographic screening among women aged 50-69 reduces breast cancer mortality but also carries some risk. This PhD project will study under- and overdiagnosis, two risks associated with mammographic screening, in BreastScreen Norway. Underdiagnosis can occur when a tumour is present but not detected as a result of screening, while overdiagnosis can occur when a woman is diagnosed with a slow growing cancer that would not become symptomatic during her lifetime.

This project will address the following topics and research questions using observational study methods.

Study 1: To determine whether tumour histopathology and survival differentially associated with potentially under- or overdiagnosed interval and screen-detected breast cancers.

* Do women with potentially underdiagnosed interval cancers have different tumour histopathology and survival than those whose interval cancers showed no signs at the prior screen?
* Do women with potentially overdiagnosed screen-detected cancer have different tumour histopathology and survival than those whose screen-detected cancer showed no signs at the prior screen?

Study 2: To estimate overdiagnosis in the screening program using individual-level data:

* What was the rate of overdiagnosis for women screened in the program during 1996-2003?
* How does adjusting for sociodemographic factors affect estimates of overdiagnosis?

Study 3: To describe awareness and knowledge about under- and overdiagnosis and breast screening in general:

* Are women aware of and knowledgeable about under- and overdiagnosis in breast screening?
* Are family doctors aware of and knowledgeable about breast screening, and under- and overdiagnosis? Are they confident in their ability to relay this information to their patients?

Study 1 is a quality improvement study and has approval from Personvernombudet (PVO 2016-4696). Study 2 has research ethics board (REK) approval (REK 2013/795), while REK approval will be sought for Study 3.

Conditions

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Breast Cancer

Study Design

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Observational Model Type

OTHER

Study Time Perspective

RETROSPECTIVE

Study Groups

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Study 1: Under- and overdiagnosed group

Non-proportional stratified sample of women diagnosed with interval or screen-detected breast cancers after participation in BreastScreen Norway. This sample will include under- or overdiagnosed cancers, as well as cancers that were not under- or overdiagnosed.

Under- or overdiagnosed cancer

Intervention Type OTHER

Diagnosed with a cancer that was visible on prior mammograms

Study 2: Rate of overdiagnosis group

Women residing in Norway, born between 1927 and 1934 (inclusive). This cohort will include women who have attended screening and who have not attended screening.

Screening

Intervention Type OTHER

Invited or attended BreastScreen Norway

Study 3: Awareness and knowledge group

Women aged 50-69, and practising family doctors aged 25-75, currently living in Norway.

No interventions assigned to this group

Interventions

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Under- or overdiagnosed cancer

Diagnosed with a cancer that was visible on prior mammograms

Intervention Type OTHER

Screening

Invited or attended BreastScreen Norway

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Breast cancer diagnosed within BreastScreen Norway using digital mammography
* Prior screening images available for review

Study 2

* Women born between 1927 and 1934 (inclusive)
* Legal resident in Norway at any time between 1996 and 2003 (inclusive)

Study 3

* Women residing in Norway, aged 50-69 (inclusive)
* Practising family doctors in Norway, aged 25-75 (inclusive)
* Provide informed consent

Minimum Eligible Age

25 Years

Maximum Eligible Age

75 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes