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Radiation Cuts Risk of Breast Cancer Return

Study Shows Benefits of Radiation After Surgery
WebMD Health News
Reviewed by Laura J. Martin, MD

Nov. 1, 2010 (San Diego) -- Radiation therapy after breast-conserving surgery cuts the risk of breast cancer returning or the risk of dying from the disease even more than doctors thought, researchers report.

Radiation therapy after surgery is now a standard option for women with early breast cancer in the U.S. and Europe.

The study of nearly 11,000 women with early breast cancer shows that the addition of radiation reduces the risk of breast cancer returning within 10 years by almost 15%, from 37.3% for surgery alone to 22.7%.

The odds of dying from breast cancer within 15 years drop by nearly 4%, from 25.4% to 21.7%.

"The findings reinforce the message that radiation substantially reduces the risk of recurrence," says Sarah Darby, PhD, a professor of medical statistics at Oxford University in England, tells WebMD. "We can also see more clearly the extent to which it reduces mortality in the long term. The reductions were bigger than expected."

"A combination of moderate gains in treatment and screening led to a halving of breast cancer [deaths] among women ages 35 to 69 in the U.K. and U.S. since the 1980s," Darby says.

Darby presented her findings here today at the 52nd Annual Meeting of the American Society for Radiation Oncology (ASTRO).

Radiation Benefits

When it comes to cancer coming back, the benefits of radiation are greatest in the first year or two after treatment, Darby says. In the first year, the risk of recurrence is 60% lower in women who get radiation, compared with women who don't, she says.

"In years two to 10, the effect continues, but is not quite as strong," she says.

The opposite pattern pertains to dying from breast cancer, Darby says.

"There is little effect in the first year. It comes on in the second year and lasts at least 10 years," she says.

By 15 years after treatment, the risk of dying from breast cancer is again similar among women who get radiation and those who don't.

Other findings from the study include:

  • The risk of dying from any cause over 15 years is about 3% lower in women who get radiation: 34.6% died vs. 37.7% of those who did not get radiation.
  • Younger women with fast-growing aggressive tumors benefit the most.

"Older women with slow-growing tumors still benefit, but not as much," Darby says.

When asked at what age a woman should be considered "younger" or "older," Darby says, "There are no set ages. The younger a woman is, the more she benefits, and the older she is the less she benefits."

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