FDA clears new device to target radiation in breast cancer patients

Tuesday, May 7th 2002, 12:00 am

By: News On 6

WASHINGTON (AP) _ More women who have a cancerous lump removed from a breast may soon have a new option for follow-up treatment: a way to radiate just the tumor site instead of the whole breast.

Targeted internal radiation, called brachytherapy, has long been available to men suffering prostate cancer, and some doctors had mastered ways to deliver radiation ``seeds'' deep into a breast as well.

But Proxima Therapeutics Inc.'s MammoSite is designed specifically for breast brachytherapy, and the Food and Drug Administration's approval Monday potentially opens the method to more widespread use in breast cancer patients.

Brachytherapy proponents welcomed the move, noting that MammoSite-style radiation treatment takes just five days instead of the seven weeks that external radiation can require. That lengthy follow-up treatment is considered one reason many women whose breast tumors are small enough and early enough to be removed via lumpectomy instead choose a more disfiguring mastectomy.

With MammoSite, ``what you have is an easier way of performing brachytherapy'' that may entice more doctors to offer it, said Dr. Frank Vicini of William Beaumont Hospital in Royal Oak, Mich., who studied the device.

MammoSite consists of a spaghetti-like catheter with an inflatable balloon that is implanted at the tumor site when the tumor is removed. Later, a radioactive seed is inserted through the catheter, and a targeted dose of radiation is emitted through the balloon. Once the patient gets enough, the catheter is removed.

``You're restricting the radiation therapy only to the tissues most likely to harbor residual cancer cells,'' Vicini explained.

He has published a study suggesting that five years after treatment, women getting brachytherapy do as well as women who got external radiation.

But some doctors worry about brachytherapy because unlike external radiation, it doesn't hit cancer cells that may lurk in other parts of the breast.

That concern made the FDA throw in a hitch. Because Proxima submitted no data proving MammoSite therapy is as effective long-term as regular radiation, the FDA ordered Proxima to state that MammoSite isn't a replacement for the whole-breast radiation that today's cancer guidelines call for following a lumpectomy.

Although doctors can use an FDA-approved medical device any way they see fit, that would seem to leave potential users in something of a quandary.

``What's not apparent at the FDA is the number of women who do not get radiation therapy today'' in direct violation of guidelines that call post-lumpectomy radiation lifesaving, said Proxima CEO Tim Patrick.

Patrick cited a National Cancer Institute study that found 25 percent of lumpectomy patients didn't receive radiation, and noted that the chances of forgoing radiation therapy increased the farther a woman lived from a clinic that offered it.

Clearly those women are a niche for MammoSite, he said. As for wider use, ``the physicians will decide.''

The American Cancer Society estimates about 203,500 U.S. women will be diagnosed with breast cancer this year. Oncologists say 70 percent will be potential candidates for lumpectomies.