Are all ductal proliferations of the breast premalignant?

The evidence for ductal proliferations of the breast being associated with the development of breast carcinoma originally came from epidemiological studies. There have now been a variety of genetic analyses of such lesions, which have shown a range of alterations from none to 37% of hyperplasias. Alterations in growth regulatory factors (steroid receptors, proliferation and apoptosis-related proteins) can also be found in a proportion of hyperplasias. The findings to date indicate that not all hyperplasias are premalignant and that the early events in breast carcinogenesis remain elusive.