[How to measure the risk of breast cancer in a population?].

One can read that one woman in 11 in France and one in nine in the USA will get breast cancer. This high risk is the result of the irrealistic assumption that all women remain exposed to the risk of breast cancer until age 90, and ignores the risk of death before that age. It is possible to allow for the occurrence of death before age 90. We describe the method, and find a risk of getting breast cancer before age 90 of one in 14 in France. The estimation of the risk of breast cancer over limited periods of life may also be useful. We describe how these estimates can be obtained, and present some results. For instance the risk of breast cancer between age 50 and 69 is one in 29, and the risk between 50 and 79 is one in 19.