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.