Mortality Evaluation Group (MEG)

Purpose: The group considers designs to evaluate the impact of population-based screening mammography on breast cancer mortality and other endpoints.

Members: Lennarth Nyström (Co-Chair), Sue Moss (Co-Chair), Ahti Antilla, Caroline Baan, Rachel Ballard-Barbash, Bill Barlow, Mireille Broeders, Harry de Koning, Eugenio Paci, Tiina Salminen, Stephen Taplin, Noel Weiss

Activities: This group has been considering ways to evaluate the effectiveness of mammography in practice. Meetings over several years have reported results from innovative controlled observational studies in Sweden and other Nordic countries. The Nordic countries have the advantage that their population registries and data systems facilitate the tracking of cohorts. In other countries without such registries, case-control evaluations have taken place. Given the controversies raised by some reviews of published trials, there is building pressure within many countries to show that programs are effective. Consideration has been given to the best method for doing this, and the growing consensus is that case-control methodologies do not offer the precision necessary to establish effectiveness in practice. Ascertaining screening exposure and separating program effects from usual care effects is nearly impossible with the widespread use of screening. The focus of the group has therefore turned to cohort studies in countries with good data systems, and identification of key process measures such as screening rates; mammography interpretive characteristics like sensitivity, specificity, and positive predictive value; recall rates; and treatment rates. Evaluation of programs in countries without registries focuses upon establishing measures of process comparable to those demonstrated in countries where programs have been shown to have an impact.