Cellular and molecular aspects of the multistage progression of mammary carcinogenesis in humans and rats.

The development of breast cancer is a multistage process. The progression of this disease in both humans and rodents has been associated with both cellular and molecular changes. The first stage, initiation, appears to be a high frequency event. Certain early progression events may be associated with oncogene activation. Further progression involves the loss of chromosomal material or gene function. In many human cancers, this is associated with mutations of the p53 gene. Certain individual women and strains of rodents are genetically predisposed to breast cancer progression. Genes predisposing individuals to breast cancer may also play a role in sporadic cancers. Although many molecular changes have been documented in mammary cells during their progression to breast cancer, they are largely descriptive. The integrated study of human breast cancer with appropriate rodent models should help provide mechanistic insight into the function of changes in the progression of breast cancer.