Contribution of three components to individual cancer risk predicting breast cancer risk in Italy.

We used data from a multicentre case-control study conducted in Italy between 1991 and 1994 on over 2500 cases of breast cancer and a comparable number of controls, and estimates of breast cancer incidence in Italy to compute individual breast cancer risk for Italian women. The estimated probabilities between age 50 and 80 ranged from approximately 5% (for a woman with no family history and low modifiable risk profile) to about 30% (for a woman with young family history and high modifiable risk) on the basis of various women's baseline characteristics. Expected numbers of breast cancer cases using the present model were compared with those based on the USA Gail model, and with the observed ones in the comparison group of the Italian Tamoxifen Trial. These show a closer agreement between the observed and the expected total numbers of breast cancers than the USA Gail model. Thus, the Gail model can be improved for use in other populations by using estimates of incidence and risk which are more appropriate to the target population.