News outlets this week reported on recently published data from a mammography screening study from Canada that was highly critical of the benefit of screening mammography.
First, it should be noted that this is not a new study. The study was conducted in the early 1980s – three decades ago – and the recent report is merely a re-review of the data.
The results of the so-called Canadian trial, first published 22 years ago, showed no benefit for screened women and as expected, the recent re-review showed the same results. The Canadian trial results are different than other randomized clinical trials, which do show benefit. When nine randomized clinical trials are combined together, including the Canadian trial, screening mammography has been shown to significantly decrease breast cancer mortality for women age 39 and older.