For breast cancer patients, targeted radiation therapy shows promise

Medical Matters

Medicine & Science

May 17, 2004|By Judy Foreman | Judy Foreman,SPECIAL TO THE SUN

Eighty-two-year-old Marie Desilets lives in Dunstable, Mass., about an hour's drive from Brigham and Women's Hospital in Boston. When she discovered that she needed radiation for breast cancer a year or so ago, she faced a dilemma.

She could get regular radiation treatments, which would involve being in Boston five days a week for seven weeks. Or she could opt for a new type of radiation that involves only 10 treatments - given twice a day for five days. In the standard method, the whole breast is irradiated; in the new one, radiation is aimed only at the exact spot where the tumor was.

Desilets chose the latter and went shopping every day between the first and second treatments.

"It was a piece of cake," she said. "I highly recommend it. I felt great the whole time."

More than half of women with relatively small tumors opt to skip a lumpectomy and instead have the entire breast removed - usually to avoid radiation. Radiation, which requires regular treatments for weeks and has side effects that include skin irritation and fatigue, is a huge hassle for those who live a long way from a medical center or whose work schedules make it difficult to spend part of every day getting treatment.

But the new procedure that Desilets had, called "accelerated partial breast radiation," is likely to change such thinking.

An estimated 71,000 women each year might be potential candidates for the procedure, which is available at many medical centers because of growing patient demand. Many insurers will pay for it.

It's too soon to say whether the new technique is ready to replace the old, which is supported by decades of practice and studies.

"The quandary is that the rationale for partial breast irradiation is compelling, but we are moving away from something that is tried and true with excellent long-term results to something that has at least something of a question mark," said Dr. Jay Harris, chief of the department of radiation oncology at Brigham and Women's Hospital and the Dana-Farber Cancer Institute.

For that reason, Harris and others suggest that women considering partial breast irradiation be treated through clinical trials, a number of which are under way or about to start.

But the risk of the new approach is probably small.

Almost all the time, when a cancer grows back in the breast where it started, it does so right in the area where the initial tumor was, not in another part of the breast, said Dr. Phillip Devlin, director of brachytherapy at Brigham and Women's Hospital and the Dana-Farber Cancer Institute. That suggests tightly targeted radiation should work.

Indeed, while radiation is important for reducing the risk of recurrence of cancer in the same breast, it does not affect overall survival. Unlike chemotherapy, whose goal is to knock out cancer cells anywhere in the body, "radiation controls local recurrence," said Dr. Oscar Streeter, associate professor of clinical radiation oncology at the Keck School of Medicine at the University of Southern California. It "does not have an effect on overall survival."

Because of its newness, partial breast irradiation is generally recommended only for women with small tumors in only one section of the breast and no signs of cancer spreading to the lymph nodes.

In one of three forms of the new procedure, called catheter-based or interstitial radiation, doctors numb the breast, then insert 10 to 20 small tubes into the area where the tumor was. They insert a radioactive "seed" containing iridium-192 into each catheter, leave it in briefly, then take it out and put it in the next catheter.

The whole procedure takes about 10 minutes, said Dr. Frank Vicini, chief of oncology at the William Beaumont Hospital in Royal Oak, Mich., and principal investigator of a new trial of partial breast irradiation in 3,000 women.

The radiation is given twice a day for five days - the tubes stay in the whole time - and provide the same tumor-killing effect as standard radiation, said Vicini, author of a 2003 study of nearly 400 women, half of whom got the new radiation and the other half whole-breast radiation.

After five years, the study showed, there was no significant difference in the rate of local recurrence.

A second approach is with a device called the MammoSite, which involves placing just one catheter into the cavity where the tumor was.

Women receiving MammoSite treatment have been followed only for about two years, but the findings look promising.

The third, and newest, approach involves an old-style external beam and is called 3D-conformal radiation or a similar technique called IMRT, for intensity-modulated radiation therapy. Instead of targeting the radiation to the whole breast, the beam is aimed with exquisite precision, using CT scans, to just the area where the tumor was.

For Marie Desilets, who had the MammoSite procedure, the new radiation was a breeze. "I didn't feel anything," she said. "My skin didn't get red. There were no repercussions at all."

Judy Foreman is a lecturer at Harvard Medical School.

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