Evidence of lipid peroxidation in premenopausal women with mammographic dysplasia.

We have compared the urinary excretion of the mutagen malonaldehyde in premenopausal women at different risks for breast cancer as determined by the appearance of the breast parenchyma on mammography. Thirty women with extensive mammographic densities were compared with 16 controls without these radiological changes. Malonaldehyde was measured in 24-h urine samples from both groups and excretion in 30 women with mammographic dysplasia (high risk) was found to be approximately double that of 16 women without these radiological changes (P less than 0.02). These results suggest that mammographic dysplasia may be associated with lipid peroxidation and raise the possibility that mutagenic products generated by this process may influence breast cancer risk.