Back to: Assess for Risk of Bias

Research Question: Does screening women using mammograms prevent death from breast cancer?

Systematic review #2: On the efficacy of screening for breast cancer

Risk of bias assessment: In response to the first systematic review, another team of systematic reviewers examined the same eight studies in 2004. They criticized the work of the first team of systematic reviewers, arguing that the six studies did not truly have a high risk of bias and should have been considered. This second team of systematic reviewers decided to analyze all eight studies.  

Systematic review conclusion: Based on all eight studies, it appeared that screening women using mammograms DOES prevent deaths from breast cancer. The systematic reviewers concluded that mammograms save lives.

Which risk of bias assessment was correct? Nearly 20 years since that first systematic review, both teams of systematic reviewers continue to defend their decisions. And there’s still some real debate about how the benefits of mammograms.