[Somatic genetics of breast cancer].

Genetic events involved in breast tumor formation are described. Abnormalities known point to determine the genes which participate in tumorigenesis. Mechanisms involved should be oncogene activation, tumor suppressor gene inactivation, abnormal protein expression. Multiple genetic alterations are probably necessary for a normal tissue to become malignant. Most of these genetic alterations seem to be somatic. Only 1 or 2 steps can be inherited and in familial cancer only (5% of breast cancers). Characterization of altered genes at somatic level during carcinogenesis will allow progress in the understanding of the molecular mechanisms involved and in the use these genetic markers in clinical oncology.