An update on mammography.

For at least 7°% of breast cancers there are no known causal factors other than gender and aging. Other possible risk factors include hormonal, genetic, nutritional, morphologic, environmental (chemical, pesticides, food additives), irradiation, and viruses. Japanese women have much less breast cancer than women in the U.S.A., and after age 45, their incidence levels off or falls, whereas ours continues to rise. Furthermore, within a generation or two of moving to the U.S.A., Japanese women have a similar incidence to ours! What are we doing that increases our risk for this disease? It would certainly suggest that the other risk factors are involved and much research continues to explore this. Screening with mammography and breast physical examination is the cornerstone of earlier detection, improved survival and reduced mortality from breast cancer. A variety of studies and improvement in stage trends support this. Despite this, overall mortality from breast cancer remains unchanged. However, increasing incidence with stable mortality would suggest there is some reduction in overall mortality. Some other reasons for no reduction in overall mortality include: I. The variable biological forms and natural history of the disease. Assuming an average 100 days doubling time, cancer has been present in a woman's breast if not elsewhere for 6-7 years or longer before it is potentially detectable by mammography or breast physical examination. The extent of disease, cell type and grade, and host resistance are all important survival factors. Not enough breast cancers are at an early stage when diagnosed and treated. Not enough eligible women are being routinely screened with optimum mammography and breast physical examination. There is too much reliance on breast self-examination and breast physical examination alone for detection.