Less Is More In Breast Radiation

Breast cancer hypofractionated radiotherapy offers long-term tumor control

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) After breast cancer surgery, radiation therapy is commonly given. Radiotherapy is used to get rid of cancer cells that can linger after surgery. Typically, the therapy is given daily for five weeks. Shorter and lower dose radiotherapy may become the new standard.

Researchers found that breast cancer relapse rates were lower in women who received lower total doses of radiation given over a shorter timeframe.

Those are the findings of a 10-year follow-up study.

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"Hypofractionation refers to delivering a shorter course of breast radiation by increasing the dose per treatment and lowering the total dose,” Benjamin Smith, MD, assistant professor of radiation oncology at The University of Texas MD Anderson Cancer Center, told dailyRx News.

Ten-year follow-up results from the UK Standardization of Breast Radiotherapy Trials (START) found that hypofractionated therapy was both safe and effective.

“Long-term follow-up confirms that a lower total dose of radiation in fewer, slightly larger fractions delivered over a shorter treatment time is at least as safe and effective as standard five-week schedules of curative radiotherapy in women with early breast cancer,” said John Yarnold, MBBS, professor of clinical oncology at The Institute of Cancer Research in London and honorary consultant at The Royal Marsden NHS Foundation Trust.

The standard dosage for five-week radiotherapy has historically been 50 Gy (a unit of absorbed energy) given in 25 small daily doses, or what physicians call fractions, according to Dr. Smith, who was not involved in this study.

The START trials involved nearly 4,500 women who had undergone surgery to remove invasive breast cancers.

A total of 2,236 were enrolled in START A. This study looked at 50 Gy (standard dosage) of radiotherapy given in 25 fractions over a five-week period compared to 39 or 41.6 Gy given in 13 sessions for five weeks.

START B, which involved 2,215 women, researchers compared 25 daily doses of 50 Gy radiation given over five weeks with 40 Gy given in 15 fractions over three weeks.

Researchers looked at how many women saw breast cancer return to the area of the original tumor after 10 years.

In the START A group, relapse rates were 7.4 percent for those who received 50 Gy in 25 sessions; 6.3 percent for women who had 41.6 Gy given in 13 sessions and 8.8 percent for those who got 39 Gy in 13 sessions over three weeks.

The START B results were even better: 5.5 percent relapse among women given 50 Gy for five weeks and 4.3 percent relapse for those who received 40 Gy given over three weeks.

Dr. Smith said of these results, “These extremely important long-term data suggest that hypofractionation is appropriate for many patients with early breast cancer receiving breast radiation. ASTRO [American Society for Radiation Oncology] has published an evidence-based guideline which identifies patients in whom all the data suggest that hypofractionation is equivalent to conventional fractionation.”

Findings from this study were presented at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium.

Before publication in a peer-reviewed journal, all research is considered preliminary.

Reviewed by: 
Review Date: 
December 5, 2012
Last Updated:
December 7, 2012