Since the options for breast cancer therapy have improved, mortality from breast cancer is falling. At the same time, however, the benefit of mammography is shrinking, as early detection screening consistently leads to overdiagnosis, while it saves fewer women’s lives.
When mammography was introduced, it was estimated that early detection of breast cancer prevented regarding twenty percent of deaths. In Norway in 1996, 731 women had to be invited to avoid dying from breast cancer. In 2016 you had to invite between 1364 and 3500 women to get the same result. The reason: “In the last 25 years, the mortality rate from breast cancer has practically halved. The positive effect of screening is diminishing as cancer treatment improves,” explained Dr. Henrik Støvring from Aarhus University.
On the other hand, the number of overdiagnoses and overtreatments, a major disadvantage of mammography, remains unchanged: one in five women gets a positive mammography result, but has a small lump that does not grow at all or grows so slowly that the woman can go on without the examination never noticed or felt breast cancer in her life. Støvring explained how overtreatment occurs: “Of course, once a cancerous lump has been discovered, it needs to be treated, although for some women this may not be necessary. We just don’t know with whom.” In addition, many thousands of women receive the news every year that they have a suspicion of breast cancer – which later turns out to be wrong.
Which: DOI 10.1093/eurpub/ckac047
