The Swedish Two-County Trial of Mammography Screening (WE)

February 5, 2018 updated by: Laszlo Tabar, MD, FACR (Hon), Dalarna County Council, Sweden

The Two-County Swedish Mammography Screening Trial

Population-based randomized controlled trial carried out in two Swedish counties, Dalarna and Ostergotland to find out the impact of early detection on mortality from breast cancer.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The Swedish Two-county study is a randomized controlled trial of invitation to mammography screening. The trial took place in Kopparberg (W), now called Dalarna, and Ostergotland counties in Sweden. The trial randomized 77,080 women aged 40-74 years to invitation to screening (active study population, ASP) and 55,985 women to no invitation to screening (passive study population, PSP). The trial started in 1977 in W-county and in 1978 in E-county. Women in age 40-49 years were invited to single-view mammography screening on average every 24 months, and women aged 50-74 years on average every 33 months. Approximately seven years after randomization a significant 31% decrease in breast cancer mortality was observed in the ASP group, whereupon the PSP was invited to screening once and the screening phase of the trial ended. The mortality data have been reported every two years during the follow-up period and published in peer-reviewed medical journals. The investigators have follow-up data to the Dec 31 2015. The 29-year follow-up data has been published in 2012 in Radiology. Publication of the long-term data reflects the fact that deaths avoided by early detection include some that would have occurred a considerable time later than the screening.

Study Type

Interventional

Enrollment (Actual)

133065

Phase

  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

40 years to 74 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Description

Inclusion criteria

  • Female
  • Aged 40-74
  • No history of breast cancer

Exclusion criteria

• Breast cancer diagnosis prior to randomization

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Screening
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Active Study Population
In the experimental arm, women aged 40-74 who were randomly selected to receive an invitation to undergo imaging with periodic single view mammography screening. This arm is referred to as the Active Study Population (ASP)
Diagnostic test: Imaging
Other Names:
  • Screening mammography
No Intervention: Passive Study Population
In the no intervention arm, women aged 40-74 who were randomly selected to not receive an invitation to undergo periodic single view mammography screening received usual care. This arm is referred to as the Passive Study Population (PSP)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Breast cancer death
Time Frame: 9 years
Comparison of breast cancer mortality in the ASP versus PSP
9 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Dalarna County Council, Sweden

Collaborators

Ostergotland County Council, Sweden

Investigators

  • Principal Investigator: Laszlo K Tabar, MD, Department of Mammography, Falun Central Hospital

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 7, 1977

Primary Completion (Actual)

September 9, 1986

Study Completion (Actual)

December 31, 2015

Study Registration Dates

First Submitted

July 11, 2017

First Submitted That Met QC Criteria

July 13, 2017

First Posted (Actual)

July 14, 2017

Study Record Updates

Last Update Posted (Actual)

February 7, 2018

Last Update Submitted That Met QC Criteria

February 5, 2018

Last Verified

February 1, 2018

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • DalarnaCC

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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