Post-lumpectomy radiation treatment for early-stage breast cancer can be safely reduced to four weeks by delivering a higher daily dose, according to the five-year results of a phase II study presented Wednesday at the 2009 American Society for Radiation Oncology (ASTRO) in Chicago.
According to the researchers, their study showed that treatment time can be shortened from the historical six to seven weeks to just four weeks using intensity-modulated radiation therapy (IMRT).
"In this phase II study, women reported acceptable side effects that were no different than would be expected from a usual, more prolonged length of treatment. In addition, with long term follow-up we see cure rates and cosmetic results that are similar to a longer six-week treatment course,” said Gary Freedman, MD, a radiation oncologist at Fox Chase Cancer Center in Philadelphia.
Using IMRT, the investigators examined the delivery of a higher daily dose of radiation over four weeks. Another way of reducing treatment length was by incorporating a "boost" into the same four weeks.
The lumpectomy site where the tumor was removed is usually treated with a high-dose radiation boost. The standard boost is typically administered after the five weeks of whole breast irradiation and can add another one to two weeks to the treatment time, according to the researchers.
The study included 75 women treated with 2.25 Gy for 20 days (versus 2 Gy per day with conventional therapy) and a 2.8 Gy boost concurrently (versus sequentially delivering the boost after whole-breast irradiation). The risk of recurrence within five years in the treated breast was only 0.4 percent, which compares favorably with results with conventional radiation. In addition, patients and their physicians considered the cosmetic results good or excellent in most women.
Freedman and his colleagues said they demonstrated that in addition to safely increasing the dose to the whole breast during the four-week period, it is possible to deliver the "boost" concurrently, eliminating the extra two weeks.
"This more accelerated treatment regimen should be an option for women who want to be treated in a shorter period of time," Freedman said. "This may particularly appeal to women who drive a long distance for radiation, have busy schedules at home or work, or have a large insurance co-pay for each daily radiation treatment."
However, Freedman cautioned that this treatment schedule may not be for all women. "There may be patients who are uncomfortable with the idea of an accelerated treatment and want to be treated with a more conventional six- to seven-week course of treatment," he said. "In addition, we need more research to determine which women are ideal candidates for this treatment because of differences in anatomy or other treatments for their breast cancer."