THURSDAY, May 31, 2007 (HealthDay News) -- A sophisticated radiation therapy system safely allows the delivery of a higher daily dose for breast cancer patients and shortens the treatment time for women from six or seven weeks to just four, researchers say.
The research team used intensity-modulated radiation therapy, or IMRT, a system that's more accurate at targeting the radiation, to see if treatment time could be shortened and the daily dose increased without any more ill effects than using the standard treatment.
"It's a bigger daily dose, but we feel it is more accurately and evenly distributed with IMRT," explained lead researcher Dr. Gary Freedman, a radiation oncologist at Fox Chase Cancer Center in Philadelphia.
His team published the findings in the June 1 issue of the International Journal of Radiation Oncology Biology Physics.
Freedman said doctors now have more options than ever before in treating breast cancer.
"We have great evidence that lumpectomy and radiation is equal, in terms of survival and cure rate, to mastectomy," at least for women with smaller tumors, he said.
Even so, the length of treatment time can still present problems. "There are many women who balk at the six- or seven-week treatment length because of perceived inconvenience, or they have to travel a lot every day [to get to treatment]," Freedman said.
The length of treatment time for radiation therapy, prescribed in combination with a lumpectomy when a woman has breast cancer, is "a very hot issue right now in radiation," Freedman said. Some studies are looking at one-week treatment with partial-breast radiation, he said, using both external beam radiation and implanted radioactive seeds.
But this approach, Freedman said, is appropriate only for a very select group of women with the smallest of breast cancers.
"My study is meant to be more inclusive," he said.
His team, which also included doctors from the University of Pennsylvania, treated 75 women, averaging 52 years of age, with a higher than typical dose of daily radiation, and then followed them to check for side effects.
"It's not a higher total dose," Freedman stressed. In traditional six- or seven-week treatments, a total of 60 grays (a unit for absorbed radiation) or Gys are given, he said. In their study, the total over the 4 weeks was 56 Gy.
The technique, not yet widespread, used a computer-controlled X-ray accelerator to deliver doses of radiation that are very precise to the tumor or to specific areas within the tumor. This specificity minimizes radiation exposure to tissues around the tumor, Freedman said.
Short-term results look good, he said. "So far, we have found that the immediate side effects of treatment were not increased over what we have seen with six or seven weeks of treatment," the researcher said. Radiation can cause skin toxicity and inflammation, for instance, but the four-week treatment results compared favorably with the results seen for conventional six- or seven-week treatment, he said.
While some women did encounter skin problems, the skin toxicity resolved within six weeks of treatment. And Freedman said the skin's cosmetic appearance was back to its pre-treatment look six weeks after treatment ended.
Longer-term follow-up is needed, he said. "We will follow [these patients] for five years," Freedman said, to be sure no long-term problems results. While previous studies have found that women who got radiation treatment in the 1980s appear to be at higher risk of heart disease than women in the general population, Freedman said he believes IMRT will better protect the heart. "We definitely reduced the dose received by the heart; we assume that means even less heart disease risk down the road," he said.
There's one downside, though: IMRT is not yet widely available, Freedman said.
Other experts said the study has both its strengths and its limitations.
Fox Chase "is a major cancer center with a long history of conducting excellent breast cancer research," said Dr. Frank Vicini, chief of oncology at the Beaumont Cancer Institute, Beaumont Hospitals, Royal Oak, Mich. But he also noted that the study had only 75 patients and needs more validation through other studies. Like Freedman, he also pointed out that the technology is not widely available.
More study will be done, he predicted. A radiation study group is already discussing trials, Vicini said.
There are other critical questions yet to be answered about any potential for long-term toxicity and recurrence, added Dr. Shawna Willey, a surgical oncologist and director of the Betty Lou Ourisman Breast Health Center at Lombardi Comprehensive Cancer Center at Georgetown University in Washington, D.C.
"If long-term toxicity and recurrence are the same as for longer treatments, most women will opt for four weeks," she predicted.
More information
To learn more about intensity-modulated radiation therapy, visit the Radiology Info.
