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Lower Dose of Radiation Therapy Just as Good as Current Regimen for Early-Stage Breast Cancer

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A British study compared the standard radiation therapy schedule to shorter, lower-dose radiation schedules and found that the risk of early-stage breast cancer coming back (recurrence) was about the same for all the schedules. The lower-dose schedules also had fewer effects on healthy breast tissue.

The research, "The UK START (Standardisation of Breast Radiotherapy) Trials; 10-year follow-up results" was presented at the 2012 San Antonio Breast Cancer Symposium.

After surgery to remove early-stage breast cancer (either lumpectomy or a type of mastectomy), radiation therapy often is used to reduce the risk of recurrence. 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 is the way radiation oncologists measure the dose of radiation therapy; if you’re on a 5-week treatment schedule, 50 Gray is the usual amount given during the 5 weeks (2 Gray at each treatment). A supplemental “boost” dose may be included at the end of the regimen that targets the area where the cancer was.

Radiation treatment schedules have been developed based on research results. But a 5- to 7-week commitment may be difficult for some women, especially if they live far away from a treatment center.

Doctors have been studying new radiation therapy schedules that involve fewer treatments with higher doses of radiation given at each treatment, but less total radiation. Also, some newer schedules are shorter than 5 weeks. These new schedules are called "low dose" or "accelerated hypofractionated" radiation therapy. The new schedules are appealing to doctors and women getting radiation 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 (or both) 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

This study, called the UK START trial, looked at three lower-dose radiation schedules to see if they were as effective as the standard schedule. The researchers also wanted to know if the lower-dose schedules had fewer effects on healthy tissue.

The study was split into two parts, A and B.

After surgery to remove early-stage breast cancer, Part A randomly assigned 2,236 women to one of three radiation schedules:

  • a total of 50 Gray in 25 treatments over 5 weeks (standard schedule)
  • a total of 39 Gray in 13 treatments over 5 weeks (low-dose)
  • a total of 41.6 Gray in 13 treatments over 5 weeks (intermediate dose)

After 10 years of follow-up, all three groups had similar recurrence rates.

There were differences in the effects on healthy tissue. Women who got the standard schedule or intermediate dose schedule had similar rates of side effects including:

  • breast induration (a hardening of some of the breast tissue)
  • shrinkage
  • swelling
  • telangiectasia (dilated blood vessels near the skin’s surface)

The women who got the low-dose schedule had a 20% lower risk of any of these side effects.

After surgery to remove early-stage breast cancer, Part B randomly assigned 2,215 women to one of two radiation schedules:

  • 50 Gray in 25 treatments over 5 weeks (standard schedule)
  • 40 Gray in 15 treatments over 3 weeks (low-dose)

After 10 years, the two groups had similar recurrence rates.

Part B showed a bigger difference in side effect rates between the two groups. Women who got the low-dose schedule were 23% less likely to have any of the side effects mentioned above.

These results suggest that a low-dose radiation therapy schedule is a good alternative to the standard schedule for women diagnosed with early-stage breast cancer. Other studies offer similar results. As life gets busier, it’s good to ask whether there is an alternative to this rigorous treatment schedule. These early results provide more information and reassurance, but it’s important to continue to get the same result consistently. This is why some doctors feel that more research is needed before they can be completely confident that low-dose schedules are as effective as the standard schedule.

If radiation therapy is part of your treatment plan, you might want to talk to your doctor about low-dose radiation therapy schedules and whether one makes sense for you based on your unique situation and specific scheduling needs.

For more information, visit the Radiation Therapy section.

Editor’s Note: In 2018, the American Society for Radiation Oncology updated its guideline on whole-breast radiation therapy. The current guideline says that most women diagnosed with breast cancer who will have radiation therapy after lumpectomy should be treated with accelerated, also called hypofractionated, whole-breast radiation therapy as the standard of care. The preferred hypofractionated dose schedule is 40 Gray in 15 doses or 42.5 Gray in 16 doses.

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