SAN ANTONIO, Texas (MCT) — Women who get lumpectomies for breast cancer may one day have a simple option involving stem cells for reconstructing the affected breast, researchers reported Saturday.

Doctors in Japan used stem cells derived from liposuctioned fat to repair the craters left in 21 women's breasts when cancerous lumps were cut out.

The lead investigator, Dr. Keizo Sugimachi, reported at the San Antonio Breast Cancer Symposium that the procedure was safe and well-tolerated in all 21 subjects, with no signs of rejection. There was a significant improvement in breast volume, and eight months later most of the women were satisfied with the outcome.

Doctors not involved in the study were cautiously optimistic the new technology might work.

"There definitely could be promise here," said Dr. David Song, chief of plastic surgery at the University of Chicago. "But a lot of issues still have to be worked out."

Dr. Marc Hedrick, president of San Diego-based Cytori Therapeutics, which developed the technology, acknowledged that the results presented Saturday were preliminary. He said two more clinical trials will be conducted next year in Europe.

"If the results hold up in more patients," he said, "that would be significant."

Currently there is no easy way to repair a breast after cancer surgery and make it look like the unaffected one. Implants, which can be used when the entire breast is removed in a mastectomy, don't work for lumpectomy patients. Often what's left of the breast is further deformed by radiation damage.

More than 100,000 U.S. women a year undergo lumpectomies and they have few cosmetic options. Some have surgical reduction of the opposite breast. Some have a flap of muscle transplanted from another part of their body. Song, the plastic surgeon, transplants skin and fat, "moving the architecture of the breast around." But all of those options are invasive.

In the new study, doctors suctioned fat from each patient, usually from her abdomen or hips. They extracted stem cells from half the fat, then mixed the cells in with the remaining fat and injected it into the lumpectomy site.

The hope is that the stem cells and other "helper cells" will keep the transplanted tissue alive.

Hedrick said the cost of the treatment, which could also be used to augment healthy breasts instead of artificial implants, would be "in the $3,000 to $5,000 range."