LONDON, England (CBS) -- Experts in Britain and Australia are using breakthrough technology to help patients with breast cancer.

It's a stem cell procedure that helps patients grow new tissue. 

Surgeons insert a plastic mold under the skin where the breast has been removed then inject it with stem cells and fat taken from other parts of the body. Blood is also pumped in during surgery to feed the cells . Researchers say new breast tissue starts to grow within six months to a year. 

But reconstructive surgeons caution this technique is still experimental.  CBS Medical Correspondent Dr. Jennifer Ashton says, "The biggest concern is that they don't want to stimulate the growth of a cancer."  She continues, "The growth factors that are used to help stimulate those stem cells and fat cells to grow and take the form of the human breast, potentially could also stimulate cancer cells." 

Doctors say they won't use the technique on women until they've been cancer-free for at least a year in case the stem cells trigger the growth of new tumors. Research is ongoing in multiple countries including the United States, but the FDA has not yet approved the technique.

Even without FDA approval, some doctors in the U.S. are already using this technology for cosmetic surgery.