As you heard from Dr. Wilkinson, the Canadian task force procedures, to this point, have focused on rating the quality of evidence, if you will, and randomized control trials are always ranked the highest. The problem is that the randomized trials were all done between the 1960s and the 1980s, at a time when mammograms where done on X-ray film that you put on the light box. They are now done digitally, and we look at the images on a computer screen. They're much more accurate. We can use software, in fact, to help us decide whether a woman has dense breasts or not.
The old trials were done, as you heard, in white populations, so the guidelines discriminate against racialized women. Now, some people say, “Why don't you just do another randomized trial?” Because those old trials, even the flawed trials, prove that mammograms save lives, it would be unethical to repeat them and expect women to go in a control group that is not having any screening.
The newer observational studies.... The one this committee needs to hear about is one called the pan-Canadian study. It was published in 2014 and ignored by our task force. It looked at 2.8 million women having screening mammograms in our provincial screening programs, and it showed that, overall, women who have mammograms are 40% less likely to die than women who don't. It's even better for women in their forties; they're 44% less likely to die. However, the task force continues to use this old data, claiming that the randomized trials trump this new, modern observational data.
We have a natural experiment in the country, which you heard about from Dr. Wilkinson. Women who live in provinces that start screening at 40 are more likely to be diagnosed with early-stage breast cancer than women who live in provinces that start at age 50, and they have better survival. In provinces that don't screen until 50, the women in their forties are diagnosed more often with late-stage cancers than women in their fifties in the same province.
This is the outcome, and our task force has never audited the outcome of the current guidelines. The current guidelines are from 2018, but they are essentially unchanged since 2011. Dr. Wilkinson and colleagues, with Statistics Canada, were able to show the damage done by those guidelines. However, from what we can see, the current review under way is likely to come up with a recommendation for no change in those guidelines.