Less radiation still effective for breast cancer

September 24, 2008 8:44:15 AM PDT
Researchers say treatment in U.S. could change radically. They are also looking at even shorter treatment times.

According to Canadian researchers, three weeks of radiation treatment work just as well as the usual course of five weeks or more for women with early-stage breast cancers. The study tracked more than 1200 women for 12 years.

After 10 years, there were no significant differences between the groups. Both had recurrence rates of 6 to 7 percent, and about 70 percent in both groups had a "good or excellent cosmetic outcome," meaning the breast did not have much discoloration, shrinkage or scarring from the radiation.

The results, presented at a conference in Boston, provide some of the strongest evidence yet that radiation schedules can safely be shortened to make life easier for patients and to let clinics reduce their waiting lists and treat more women without buying more machines.

Experts say the new findings, from a respected study, could change the standard of care in the United States. The typical schedule now involves five to seven weeks of daily treatments, and most women would welcome a chance to get it over with faster ? especially those who work, have small children or live far from the clinic.

Some centers in this country already offer shorter courses of treatment, but they are more widely available in Canada and parts of Europe.

"We've really got to give it serious consideration in the United States," said Dr. Anthony L. Zietman, a radiation oncologist at Harvard Medical School and the Massachusetts General Hospital Cancer Center, and president-elect of the American Society for Therapeutic Radiology and Oncology. He was not involved in the Canadian study.

But Dr. Zietman cautioned that the results applied only to women with early cancers like those in the study, which were removed by lumpectomy and had not spread to the lymph nodes. Often, women with such early cancers do not need chemotherapy.

Other major changes in radiation are also in the works. Doctors are experimenting with ways to treat just part of the breast rather than all of it, and to make the treatment safer, they are trying to avoid exposing the heart and lungs to radiation.

The purpose of radiation is to keep cancer from coming back in the same breast where it first occurred, by killing any tumor cells that may have evaded surgery and chemotherapy. Cancer cells are more vulnerable to radiation than are normal ones, and the treatment has always been a balancing act between giving enough radiation to destroy the tumor cells but not enough to cause serious damage to healthy tissue and organs.

The changes now being made result in part from the overall success in treating early breast cancers, Dr. Zietman said. Survival rates have climbed so high ? 98 percent of women with early-stage cancers survive at least five years ? that it is now considered reasonable to step back, look at women's quality of life and try modifying the regimens to make treatment less onerous.

"It's a bit of a change in our thinking," Dr. Zietman said.

Researchers also hope that faster treatment will help make radiation available to more women. Currently, about 20 to 30 percent of women in North American who need it skip it. And some women who could have lumpectomy plus radiation choose mastectomy instead, simply to avoid radiation, because they live too far from a clinic to travel back and forth for all the treatments.

Not all medical centers offer the newer techniques, and they are not right for every woman. But for many women, there are choices now where none existed before ? though it may take some effort to find out about them.

"Patients have to speak up," Dr. Zietman said.

If the standard regimen is recommended, he said, a woman should ask: "Does it have to be that way? Am I one of the people who could be treated with partial breast irradiation, or, if I need the whole breast treated, could it be done in some more abbreviated fashion?"

He added, "Maybe they can, maybe they can't."

Some radiation oncologists may resist change, fearful of giving up the tried and true formulas they were taught, Dr. Zietman said. He noted that the standard treatment had 30 years of evidence to back it up, whereas the newer approach had less than half that. But still, the field is moving ahead.

"You don't give all women with breast cancer the same treatment," he said. "You base it on what they have, and who they are."

Canadian researchers decided to study the shorter courses because doctors there and in England had begun using them without a formal trial, to make the most of a limited number of radiation machines.

Medical centers are also experimenting with techniques that could shorten the treatment to a few days or even just one day for some women. Those techniques involve treating only about a quarter of the breast, the part nearest the tumor, and the radiation can be given with a machine or with radioactive seeds that are temporarily implanted into the cavity left by lumpectomy. In some cases the entire dose of radiation is given before the patient leaves the operating room.

The partial breast treatments are still being studied, and although the results look promising, more time for follow-up is needed to be sure, Dr. Zietman said.


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