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No Increase in Long-Term Side Effects With Weekly Hypofractionated Radiation Schedule

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After lumpectomy to remove early-stage breast cancer, an accelerated radiation therapy schedule of treatment once per week for 5 weeks offers about the same rate of long-term side effects as a traditional schedule of daily treatment for 5 weeks, according to a study.

The research was presented on Oct. 21, 2018, at the American Society for Radiation Oncology (ASTRO) Annual Meeting. Read the abstract of “FAST Phase III RCT of Radiotherapy Hypofractionation for Treatment of Early Breast Cancer: 10-Year Results (CRUKE/04/015).” (PDF; refer to LBA2)

Hypofractionated vs. traditional radiation therapy schedules

Women diagnosed with early-stage breast cancer who have lumpectomy to remove the cancer usually have radiation therapy after surgery. Radiation therapy after lumpectomy lowers the risk of the cancer coming back (recurrence) and makes lumpectomy as effective as mastectomy.

Whole-breast radiation therapy after breast cancer surgery is usually given as one treatment per day, 5 days a week, for 5 to 7 weeks. A Gray, abbreviated Gy, is the way radiation oncologists measure the dose of radiation therapy; if you’re on a 5-week treatment schedule, 50 Gy is the usual amount given during the 5 weeks (2 Gy at each treatment). A supplemental “boost” dose that targets the area where the cancer was may be included at the end of the regimen.

Radiation treatment schedules were developed based on research results. But a 5- to 7-week nearly daily commitment may be difficult for some women, especially if they live far away from a treatment center. So doctors developed and studied different radiation therapy schedules that involve fewer treatments with higher doses of radiation at each treatment, but about the same total radiation dose. This accelerated, or hypofractionated, radiation schedule puts the same radiation dose into a 3- to 5-week schedule.

A hypofractionated whole-breast radiation schedule is appealing to doctors and people getting radiation therapy for several reasons:

  • Convenience -- arranging daily trips to get treatment can be a problem for some women; fewer treatment days or a shorter period of time may be easier to schedule.
  • If radiation is more convenient to schedule, it’s probably easier for women to get all the recommended radiation therapy.

In March 2018, updated guidelines on whole-breast radiation therapy from ASTRO said that most women diagnosed with breast cancer should be treated with hypofractionated whole-breast radiation as the standard of care.

The FAST trial

This British study, called the FAST trial, included 915 women aged 50 or older who had been diagnosed with early-stage breast cancer. All the women had lumpectomy and all were scheduled to receive radiation therapy after surgery. None of the women were treated with chemotherapy.

The women were randomly assigned to one of three radiation schedules:

  • 2 Gy daily for 5 weeks for a total of 50 Gy; the traditional schedule
  • 6 Gy once a week for 5 weeks for a total of 30 Gy; a hypofractionated schedule
  • 5.7 Gy once a week for 5 weeks for a total of 28.5 Gy; another hypofractionated schedule

None of the women were treated with a boost dose of radiation.

After 10 years of follow-up, rates of moderate and severe skin side effects were:

  • 14.6% for the 5.7 Gy per week schedule
  • 9.1% for the 2 Gy daily schedule

The difference in side effect rates was not statistically significant, which means that it could have been due to chance and not because of the difference in radiation therapy schedules.

But with the 6 Gy per week schedule, rates of moderate to severe skin side effects at 10 years were significantly higher compared to the traditional schedule: 18.4% vs. 9.1%, respectively.

Women treated with the 6 Gy per week schedule were two to three times more likely to have hardening or shrinking of breast tissue, spider veins, or a build-up of fluid in the treatment area.

The study also looked at recurrence rates for the three radiation schedules. Overall, there were only 10 breast cancer recurrences among all the women in the study:

  • three in the 2 Gy daily schedule
  • three in the 6 Gy per week schedule
  • four in the 5.7 Gy per week schedule

“This was always a trial to see if five fractions were feasible, and I think we’ve shown that it is,” said lead researcher Murray Brunt, M.D., of University Hospitals of North Midlands and Keele University, at a media briefing on the study. “We’re not suggesting that general fractionation should change. For those frail patients, I actually think this is enough to discuss it with them.”

Deciding on a radiation schedule that’s right for you

"The ASTRO guidelines apply to most women diagnosed with breast cancer," said Marisa Weiss, M.D., chief medical officer and radiation oncologist. "There are some exceptions, however. The ability to deliver a larger dose requires that your doctor design a radiation treatment plan that is very even throughout the whole area of the breast. Sometimes this is hard to achieve. In women with very large breasts or who have a large chest size, it may be hard to achieve an even dose, so your doctor may recommend a traditional dose schedule.

"It is important for each person to get the best care possible for her unique situation," she continued. "The hypofractionated schedule is likely more convenient and less disruptive in your busy life. Still, if you have to have a longer treatment plan, don’t think that this means you have a worse situation or worse outcome. The schedule has no impact on prognosis or how well you do."

If you’ve been diagnosed with early-stage breast cancer, have had lumpectomy, and radiation therapy is part of your treatment plan, it makes sense to ask your doctor about this study and the ASTRO guidelines and whether hypofractionated whole-breast radiation makes sense for you and your unique situation.

It’s also a good idea to talk to your doctor about skin reactions to radiation -- together you can develop a plan to ease any skin irritation that happens during and after radiation therapy.

For more information, including managing skin side effects, visit the Radiation Therapy section.

To talk with others going through radiation treatment, join the Discussion Board forum Radiation Therapy - Before, During, and After.

Written by: Jamie DePolo, senior editor

Reviewed by: Brian Wojciechowski, M.D., medical adviser

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