A study compared the standard radiation therapy schedule to a shorter, lower-dose radiation schedule and found that the risk of the cancer coming back (recurrence) after lumpectomy to remove early-stage breast cancer was the same for both schedules.
After lumpectomy, radiation therapy often is used to reduce the risk of recurrence. Radiation therapy after breast cancer surgery is most commonly given as 25 treatments -- you're treated 5 times per week for 5 weeks. A Gray is the way radiation oncologists measure the dose of radiation therapy; 50 Gray is the usual amount given during the 5 weeks (2 Gray at each treatment).
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
- less overall radiation exposure
- if radiation is more convenient to schedule, it's probably easier for women to get all the recommended radiation therapy
- total cost may be lower
This study wanted to know if one of these low-dose radiation therapy schedules was as effective as the standard schedule. After lumpectomy, half of the 1,224 Canadian women in the study got radiation therapy on the standard schedule over 35 days (5 weeks). The other 612 women got radiation therapy on a low-dose schedule:
- 16 total treatments given as five treatments per week, over 22 days (3 weeks and 1 day); 2.65 Gray was given at each treatment for a total of 42.5 Gray
The women were followed for about 12 years after completing radiation therapy. The long follow-up time gives doctors more confidence in the results.
The risk of cancer coming back during the 10 years after diagnosis was the same for both radiation therapy schedules:
- 6.2% of the women who got the low-dose radiation therapy schedule had a recurrence compared to 6.7% of the women who got the standard schedule; this difference wasn't significant, which means it could have been due to chance and not because of the different schedules
Cosmetic results during the 10 years were the same for both schedules:
- 71.3% of the women who got the low-dose radiation therapy schedule had a good or excellent cosmetic result compared to 69.8% of the women who got the standard schedule; this difference also wasn't significant, which means it could have been due to chance and not because of the different schedules
These results suggest that a low-dose radiation therapy schedule is a good alternative to the standard schedule. Other studies have offered similar results. Still, 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.
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.