The Swedish Two-County Trial of Mammography Screening

Not Applicable

Completed

• Conditions: Breast Neoplasm Female
• Interventions: Diagnostic Test: Imaging

• Registration Number: NCT03217539
• Lead Sponsor: Dalarna County Council, Sweden

Brief Summary

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.

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 Timeline

• Study Start: 1977-07-07
• Primary Completion: 1986-09-09
• Study Completion: 2015-12-31
• Study First Submitted: 2017-07-11
• Study First Submitted QC: 2017-07-13
• Study First Posted: 2017-07-14
• Status Verified: 2018-02
• Last Update Submitted: 2018-02-05
• Last Update Posted: 2018-02-07

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 133065

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Active Study Population	Imaging	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)

Primary Outcome Measures

Name	Time	Method
Breast cancer death	9 years	Comparison of breast cancer mortality in the ASP versus PSP