WEDNESDAY, Oct. 19 (HealthDay News) -- Women with breast cancer who undergo radiation after a lumpectomy have significantly fewer recurrences and, consequently, greater odds of survival than women who forgo radiation, new research says.
The study also noted no long-term adverse effects from radiation after this breast-conserving surgery, as deaths from any cause were also reduced substantially.
"For the first time, this showed this important linkage between using radiation to avoid local recurrence and improving long-term survival," said Dr. Jay Harris, chairman of radiation oncology at Dana-Farber Cancer Institute and Brigham & Women's Hospital in Boston. "Up until 2005, the prevailing attitude in the U.S. was that radiation did not have an impact on improving long-term survival and was strictly to reduce local recurrence."
Giving radiotherapy after breast-conserving treatment is already common practice, said Dr. Shelly Hayes, a radiation oncologist with Fox Chase Cancer Center in Philadelphia. The point is to destroy any stray cells in the affected breast.
The findings echo the results of a landmark 2005 paper that involved fewer women and shorter follow-up. They should help erase any lingering doubts among skeptics, experts said.
"It is going to be very helpful to see updated results with lots more patients, lots more follow-up and this is very substantial improvement in long-term outcome," Harris said.
Here, the authors assessed data on almost 11,000 women in 17 randomized trials that compared radiation with no radiation after lumpectomy.
The authors took the unusual step of including both published and unpublished trials, making "the data very reliable," said Harris.
Overall, irradiating the affected breast halved recurrence rates and cut the mortality rate by one-sixth, the researchers said.
After 10 years, 19 percent of women who had undergone radiation had had a recurrence compared with almost twice as many -- 35 percent -- in the non-radiation group.
And 15 years after diagnosis, 25 percent of women with radiation were alive, vs. 21 percent in the control group. At that time, the absolute risk reduction in all-cause mortality was 3 percent, the study found.
The numbers varied according to age, grade of tumor, estrogen-receptor status, whether the patient had taken the estrogen-suppressing drug tamoxifen and how extensive the surgery had been.
"The magnitude of the benefit got smaller with more favorable factors, but there were benefits in every subgroup, which translated into benefit in terms of recurrence risk, which translated into overall survival," Hayes said.
"Across the board, no matter what those features were, women benefited from radiation," Hayes said.
For some time, doctors have wondered whether radiation was really necessary for all women, said study co-author Sarah Darby, professor of medical statistics at the University of Oxford in England.
"These findings will enable both doctors and patients to have a better idea of the benefit that is likely to be gained from radiotherapy on a patient-by-patient basis," she said.
The U.S. National Cancer Institute has more on breast cancer treatments.
SOURCES: Sarah Darby, Ph.D., professor, medical statistics, University of Oxford, England; Shelly Hayes, M.D., radiation oncologist, Fox Chase Cancer Center, Philadelphia; Jay R. Harris, M.D., professor and chairman, radiation oncology, Dana-Farber Cancer Institute and Brigham & Women's Hospital, Boston; Oct. 20, 2011, The Lancet, online
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