Seven landmark studies in North America and Europe, conducted in the 1970s, together suggested regular screening lowers the risk of breast cancer death by about 30 percent. Swedish studies conducted since mammograms have become routine found that those who comply with screening recommendations reduce their risk of dying from breast cancer by 63 percent when compared to the early 1970s. For all women in the Swedish population, the risk of dying from breast cancer has fallen 50 percent since the 1970s. It is not yet clear the degree to which improving breast cancer survival results from catching the disease earlier through screening or from better treatments once it is detected. There is also the possibility that those who get mammograms are already healthier than those who do not. Their good habits, not their mammograms, make them live longer.
Breast cancer most often begins in the cells lining the milk ducts. An experimental technique known as ductal lavage, involves "washing" breast milk ducts with saline and examining cells for signs of precancerous or cancerous changes.
Mammograms increase the risk for developing breast cancer and raise the risk of spreading or metastasizing an existing growth. The high sensitivity of the breast, especially in young women, to radiation induced cancer was known by 1970. Nevertheless, the establishment persists in screening women under 50 with X-ray dosages so high as to increase breast cancer risk by up to 20 percent, while safe alternatives exist but are ignored.
The annual mammographic screening of 10,000 women aged 50-70 will extend the lives of, at best, 26 of them; and annual screening of 10,000 women in their 40s will extend the lives of only 12 women per year.
Since the 1980s, the Canadian National Breast Screening Study has been following more than 39,000 women who received either an annual physical breast examination or an examination plus mammography. Breast cancer detection for both groups was about the same: 622 for the mammography group and 610 for the physical exam-only group. However, breast cancer detection averaged about two years earlier for the mammography group. There were 88 deaths among the women who had examinations plus mammography, compared with 90 for the physical exam-only women. However, since the cancer was detected earlier with mammography, it would seem as if the women were living longer. Actually, they were living longer only in relation to the date of diagnosis. An earlier diagnosis would seem to give them a longer survival rate, when, in fact, they were dying at the same rate as always.