There were, in fact, 11 randomized controlled trials. The first one was done in 1963. It was in New York, and it was called the HIP, which stood for their health insurance plan. Then there were several in Sweden. There were Malmö 1 and Malmö 2, Kopparberg and Östergötland, and then Edinburgh had a trial. Two of them were the CNBSS trials. CNBSS 1 was for women aged 40 to 49, and CNBSS 2 was for women aged 50 to 59. They were completely different trials with different methods. Then there was Stockholm, Gothenburg and Finland. Of all the randomized trials, the Canadians were the only ones that didn't show reduced deaths in the mammogram arm.
On December 6th, 2023. See this statement in context.