ASCO: Less Adjuvant Radiation Safe in Early Breast Cancer

CHICAGO, June 3 -- For early node-positive breast cancer, an abbreviated course of adjuvant radiation with fewer fractions and a lower total dose does not appear to add to the risk of local recurrence, British researchers said here."It is likely that patients can be safely and effectively treated to a lower total dose with fewer fractions," said John Dewar, M.D., of the University of Dundee in Scotland while reporting the results of two multicenter phase III trials at the American Society of Clinical Oncology meeting.
Currently, he said, the standard British treatment for woman who have had definitive surgery for invasive disease (stage T1-3, N0-1, M0) is 50 Gy in 25 fractions over five weeks.
"We initiated the START trials (Standardization of Breast Radiotherapy) to see whether we could reduce the time to undergo treatment," Dr. Dewar said. He said that oncologists recruited 2,236 women in START-A and divided them into three treatment groups.
He said 749 women were treated with standard regimen, receiving 50 Gy over five weeks. A second group of 750 women received 41.6 Gy in 13 fractions of 3.2 Gy over a five-week course; the third group of 737 women received 39 Gy as a total dose in 13 fractions of 3 Gy over five weeks.
In START-B, researchers randomized 2,215 women to receive either the standard dose or 40 Gy in 15 doses of 2.67 Gray over a three-week period.
The results were all about the same, Dr. Dewar said. "Cancer control in the breast was very effective in all groups," he said. "About 3.4% of the women had a relapse in the same breast after five years -- less than 1% per year." There were no statistically significant differences among any of the groups in recurrence rates, he said.
"What this means," he said, "is that we can deliver less radiation in lees time and still maintain very effective cancer control."
In addition he suggested that the studies will allow radiation oncologists to conduct further studies of fractions of radiation in doses less that 2 Gy, as well as allow intensity adjustments to individualized patients.
"This is exciting news for our patients," said medical oncologist Julie Gralow, M.D., of the University of Washington in Seattle, who moderated a press briefing where the British trials were discussed. "For many patients who have to travel long distances for treatment the ability to reduce time away from home from five weeks to three weeks is meaningful."
Dr. Gralow also suggested that reduction in dose could also reduce the rate of breast fibrosis and lymphedema.