The Swedish Two-County Trial of Mammography Screening

NCT ID: NCT03217539

Last Updated: 2018-02-07

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 133065 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 1977-07-07
• Study Completion Date: 2015-12-31

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.

Conditions

Breast Neoplasm Female

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: SCREENING
• Blinding Strategy: NONE

Study Groups

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)

Group Type: EXPERIMENTAL

Imaging

Intervention Type: DIAGNOSTIC_TEST

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)

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

Imaging

Intervention Type: DIAGNOSTIC_TEST

Other Intervention Names

Screening mammography

Eligibility Criteria

Inclusion Criteria

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

Exclusion Criteria

• Breast cancer diagnosis prior to randomization

• Minimum Eligible Age: 40 Years
• Maximum Eligible Age: 74 Years
• Eligible Sex: FEMALE
• Accepts Healthy Volunteers: No

Sponsors

Ostergotland County Council, Sweden

OTHER

Sponsor Role: collaborator

Dalarna County Council, Sweden

OTHER

Sponsor Role: lead

Responsible Party

Laszlo Tabar, MD, FACR (Hon)

Emeritus Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Laszlo K Tabar, MD

Role: PRINCIPAL_INVESTIGATOR

Department of Mammography, Falun Central Hospital

Other Identifiers

DalarnaCC

Identifier Type: -

Identifier Source: org_study_id