"You cannot even see the cells. It looks like a clear solution, [but] there are cells in there. Remember they're very tiny."

In this laboratory at Michigan State, researcher James Trosko grows breast stem cells. He's been doing it for twelve years. It started from adult breast tissue salvaged after breast reductions, and it's what Trosko says has helped him and his colleagues come closer to understanding the origins of breast cancer.

"The stem cells body, indeed, are probably the main target cells for cancer."

A woman's breast has a variety of different cells, but it's the breast stem cell that, Trosko says, can easily develop into cancerous cells. Why? Because the two are so alike.

"They share many of the same properties. These stem cells are immortal, so are cancer cells. They are immortal. Stem cells are very primitive. Cancer cells are very primitive."

This discovery, in turn, may help treat breast cancer more effectively. That's because current treatments target an entire tumor.

"It seems that the only cell in this large mass that can perpetuate the growth of that tumor is the cancer stem cell."

So, Trosko says, if cancerous stem cells can be identified within a tumor, they can be erradicated and the growth and spread of cancer will stop. It's research that's one step closer to helping find a cure for a disease that strikes women everywhere.