According to British Medical Journal (BMJ) article Researchers in Canada conducted a Randomized Screening Trial regarding incidence and mortality from breast cancer in women who have had mammography done as a screening method. Research data includes follow-ups done up to 25 years in women aged 40-59 years. In this study women who had mammograms done on them were compared to women who did not have it done (controls).
Results of trial found that cumulative mortality from breast cancer was similar for women had mammograms compared to women who didn’t have it. In a 15-year follow-up, 106 breast cancers were detected due to overdiagnosis. Thus in women aged 40-59 years annual mammography does not reduce mortality compared to women who have only had a physical examination as a screening method for breast cancer. Also about 22% (106/484) cases of invasive breast cancer detected were overdiagnosed i.e. 22 % women who got diagnosed with breast cancer by mammography did not have breast cancer.
The research was done at 15 cancer screening center in Canada. The study included 89,835 women aged 40-59 years including both mammography group (Women who had got mammograms done) and controls (Women who did not have mammograms done and had physical examination only). During five-year screening period, 666 invasive breast cancers were diagnosed in the mammography group ( included 44 925 participants) and 524 in the controls (included 44 910), and of these, 180 women in the mammography arm and 171 women in the control group died of breast cancer during the 25 year follow-up period.
