An extra dose of radiation aimed squarely at the spot where the tumor was removed can substantially improve the outlook for younger women with breast cancer, a European study found.
The treatment, already routine at many U.S. hospitals, cut the risk of a recurrence of cancer nearly in half during five years of follow-up for women under 40.
The study looked at 5,569 patients from the Netherlands, France and Belgium. All got a five-week series of whole-breast radiation treatments after having their tumors surgically removed; 2,661 got a second, shorter series of radiation aimed at the spot where the cancer had been.
Overall, 7.3 percent of the women in the standard treatment group developed new tumors, compared with 4.3 percent of those who got the extra radiation.
But for the women 40 or younger _ who have the greatest risk of new tumors _ the benefit was far greater. Forty-six _ 19.5 percent _ of the 228 who got the standard treatment developed new tumors within five years, compared with 10.2 percent, or 22, of the 221 who got the booster dose.
The study was published in Thursday's New England Journal of Medicine and was led by Dr. Harry Bartelink of the Netherlands Cancer Institute.
``I think the findings are important and significant, but they're not surprising,'' said Dr. Skyler Lindsley, a specialist at the Seattle Cancer Care Alliance and the University of Washington Medical Center.
She estimated that 80 percent of U.S. clinics have been using the booster dose for years _ 10 years at UWMC. ``It's nice to see confirmation of a practice that we've been doing for some time,'' she said.
She said it has few side effects and is routinely used among older patients as well as younger ones.
Because of the latest study, the booster dose probably will become standard treatment everywhere, she said.