Stem cell may drive breast cancer

http://news.bbc.co.uk/1/hi/health/4581694.stm

Recurring breast cancer could be caused by newly discovered rare stem cells transformed into a "tumour factory" by genetic errors, scientists have said. Researchers believe that as well as driving all breast development, the cells may have a key role in cancer.
The Australian team transplanted the cells into mice tissue and were able to grow a fully-functioning breast.
Writing in Nature, they say they also found the key stem cells were more numerous in pre-cancerous tissue.
The research holds out hope on two fronts: the possible development of new cancer therapies, and of new techniques for breast reconstruction.