Patient-reported outcome information from a study comparing partial-breast radiation to whole-breast radiation shows that for women who don’t have chemotherapy after surgery, partial-breast radiation:
- was more convenient
- caused less post-treatment fatigue
- caused slightly poorer cosmetic results
The research was presented on June 3, 2019, at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting. Read the abstract of “Patient-reported outcomes (PROs) in NRG oncology/NSABP B-39/RTOG 0413: A randomized phase III study of conventional whole breast irradiation (WBI) versus partial breast irradiation (PBI) in stage 0, I, or II breast cancer.”
Partial- vs. whole-breast radiation
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.
Radiation can be delivered to the entire breast — called whole-breast radiation — or to just the area of the breast where the cancer was — called partial-breast radiation.
Traditional whole-breast external beam radiation therapy aims cancer-destroying energy at the whole breast. The source of the radiation is outside the breast, which is why it's called “external beam.” Whole-breast radiation therapy is usually given as one treatment per day, 5 days a week, for 5 to 7 weeks. A Gray (Gy) is the unit radiation oncologists use to 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 may be included at the end of the treatment regimen that targets the area where the cancer was.
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.
To overcome the drawbacks of traditional whole-breast radiation therapy, doctors have developed different ways to deliver radiation. Partial-breast radiation delivers a higher dose of radiation to a smaller area of the breast over a shorter period of time compared to traditional whole-breast radiation therapy.
There are three types of partial-breast radiation:
- 3D conformal external beam radiation therapy (3DCRT) uses a linear accelerator, the same machine used to deliver whole-breast external beam radiation. But instead of aiming radiation at the whole breast, a special MRI or CAT scan of the breast is done and used to map out small treatment fields for the area at risk. The type and distribution of radiation are designed to maximize the dose of radiation to the area that needs to be treated and avoid or minimize radiation to tissue near the area. Radiation treatments are done once or twice a day for 1 week.
- Multi-catheter internal radiation, also called interstitial needle-catheter brachytherapy, uses radioactive “seeds” to deliver radiation directly to the area where the cancer was. The seeds are placed in very small tubes (catheters) that are stitched into place under the skin. The seeds are left in the tubes for a few hours or a few days, and you remain in the hospital during treatment. Once the treatment is completed, the seeds, tubes, and stitches are removed and you go home.
- Balloon internal radiation, known by the brand name MammoSite, places a special tube with a balloon on one end in the breast where the cancer was. The tube comes out of the skin through a small hole. The tube and balloon are placed either during lumpectomy or afterward in a surgeon's office. During each treatment, a machine places a radioactive seed into the center of the balloon for 5 to 10 minutes — just long enough to deliver the required dose of radiation. After the seed is removed, you may leave the treatment center. A total of 10 treatments are usually given over 5 days. That means two treatments per day, about 6 hours apart. When the final treatment is done, the balloon and tube are removed through the small hole in the skin.
Comparing effectiveness of the two types of radiation therapy
Results from NSABP B-39/RTOG 0413 study presented at the 2018 San Antonio Breast Cancer Symposium found that partial-breast radiation after lumpectomy was slightly less effective than whole-breast radiation at reducing the risk of breast cancer recurrence in the same breast in women diagnosed with early-stage breast cancer.
“The results show that partial-breast radiation is pretty close to whole-breast radiation, but not exactly the same,” said Marisa Weiss, M.D., radiation oncologist and Breastcancer.org chief medical officer and founder. “Recurrence was a little higher in women treated with partial-breast radiation, but the difference was small. Partial-breast radiation remains an important option for certain women.”
In this latest analysis of data from the NSABP B-39/RTOG 0413 study, researchers wanted to know what women treated with both types of radiation thought about the results.
“While PBI recurrence outcomes were statistically inferior to WBI on the NRG Oncology NSABP B-39/RTOG 0413 trial, it is still crucial that we measure how PBI compares to WBI in terms of quality of life for women,” said Patricia Ganz, M.D., director of Cancer Prevention and Control Research at the University of California, Los Angeles Jonsson Comprehensive Cancer Center. “As there were only slight clinical outcome differences between these two treatments, some women could still derive benefit from PBI treatment in terms of outcomes such as cosmesis or fatigue.”
Ganz, who is also a member of the Breastcancer.org Professional Advisory Board, presented the research at the ASCO Annual Meeting.
The analysis included 950 women:
- 446 women also were treated with chemotherapy
- 504 women were not treated with chemotherapy
The women were asked about a number of quality of life factors, including:
- cosmetic appearance of the treated breast
- physical functioning
- convenience of care
The women were asked about these factors before the study started, when treatment was completed, 4 weeks after treatment was completed, and 6, 12, 24, and 36 months after treatment was completed.
Women treated with partial breast radiation who did not receive chemotherapy reported:
- less fatigue
- slightly poorer cosmetic outcomes
compared to women treated with whole-breast radiation who did not receive chemotherapy.
Women who were not treated with chemotherapy also reported that partial-breast radiation was more convenient than whole-breast radiation.
Women treated with partial-breast radiation who also were treated with chemotherapy reported:
- more fatigue
- equal cosmetic outcomes
compared to women treated with whole-breast radiation and chemotherapy.
“The size of the differences were relatively small,” Ganz said during her presentation, adding that the differences seen may have little clinical meaning. “Because of its shorter course and greater perceived convenience in women who did not receive chemotherapy, partial breast irradiation may be a good option for some patients.”
What this means for you
If you’ve been diagnosed with stage 0, stage I, or stage II breast cancer and will be having lumpectomy followed by radiation, you and your doctor may be considering partial-breast radiation as an alternative to traditional whole-breast radiation therapy. Perhaps the daily trips to the treatment center would be a burden because of distance, your job, or other commitments. Talk to your doctors about the various types of partial-breast radiation and their experience with each of the delivery methods.
The Breastcancer.org Radiation Therapy pages have more information on both whole-breast and accelerated partial-breast radiation therapy.
To discuss all types of radiation therapy and its effects with others, join the Breastcancer.org Discussion Board forum Radiation Therapy - Before, During, and After.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser