The American Society for Radiation Oncology (ASTRO) has put out updated guidelines on accelerated partial breast irradiation for early-stage breast cancer.
The updated guidelines suggest that more people diagnosed with early-stage disease can benefit from accelerated partial breast irradiation, including younger women and women diagnosed with low-risk DCIS.
The updated guidelines were published online on Nov. 17 by the journal Practical Radiation Oncology. Read “Accelerated Partial Breast Irradiation: Executive summary for the update of an ASTRO Evidence-Based Consensus Statement.”
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 accelerated partial breast radiation.
Traditional external beam radiation therapy aims cancer-destroying energy at the whole breast or to the area of the breast where the cancer was. The source of the radiation is outside the breast, which is why it's called "external beam." Many studies have shown the long- and short-term effectiveness of external beam radiation therapy. The drawbacks of traditional radiation therapy include daily trips to the hospital for treatments -- typically 5 days a week for 4 to 6 weeks. Traditional radiation therapy also has a large field and may expose healthy tissue, such as the heart and lungs, to radiation.
To overcome the drawbacks of traditional external beam radiation therapy, doctors developed different ways to deliver radiation. Accelerated partial breast irradiation delivers a higher dose of radiation to a smaller area of the breast over a shorter period of time compared to traditional external beam radiation therapy. There are three types of accelerated partial-breast irradiation:
- Multi-catheter internal radiation, also called interstitial needle-catheter brachytherapy. This approach 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. 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. This approach 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.
- 3-D conformal external beam radiation (3DCRT). This experimental approach starts with a planning session (simulation). A special MRI or CAT scan of the breast is done and is used to map out small treatment fields for the area at risk. The type and distribution of radiation is designed to maximize the dose to the area that needs to be treated and avoid or minimize radiation to tissue near the area. The radiation is delivered with a linear accelerator, the same machine used in traditional external radiation, twice a day for 1 week.
To write the updated guidelines, ASTRO experts reviewed 44 studies on accelerated partial breast irradiation published from 2008 to 2016.
The updated guidelines say:
- Women age 50 or older should be considered suitable for accelerated partial breast irradiation. Women ages 40 to 49 who meet other criteria should be considered “cautionary,” and women younger than 40 or who do not meet the criteria should be considered unsuitable. Previous guidelines said that women needed to be 60 or older to be considered suitable for accelerated partial breast irradiation.
- Women diagnosed with DCIS at low risk for recurrence should be considered suitable for accelerated partial breast irradiation if they meet all aspects of the definition of low-risk DCIS, including screening-detected disease, a tumor size of 2.5 cm or smaller, and clean surgical margins that are 3 mm or larger. Previous guidelines had no women diagnosed with DCIS in the suitable group for accelerated partial breast irradiation.
- Women diagnosed with early-stage breast cancer are considered suitable for accelerated partial breast irradiation if clean surgical margins are 2 mm or larger. Women with clean surgical margins that are close to or smaller than 2 mm are considered cautionary. This recommendation is the same as it was in previous guidelines.
"As trials mature and evidence accumulates, we can understand more comprehensively who benefits from accelerated radiation treatment following lumpectomy, and we are finding that the pool of suitable candidates for this emerging treatment is larger than first anticipated," said Jay R. Harris, M.D., chair of the task force that developed the guidelines and distinguished professor of radiation oncology at the Dana-Farber Cancer Institute at the Harvard Medical School. "Carefully selected patients may achieve similar tumor control following shorter, targeted schedules of radiation as they would with weeks of radiation to the whole breast."
The updated guidelines also provide recommendations for using intraoperative radiation therapy for early-stage breast cancer. Intraoperative radiation therapy (sometimes abbreviated IORT) is a relatively new way to give radiation therapy. During surgery to remove breast cancer, radiation is given as a single dose directly to the area where the cancer used to be.
The recommendations for intraoperative radiation therapy say:
- Doctors should tell women that the risk of recurrence may be higher with intraoperative radiation therapy compared to whole breast radiation.
- Electron beam intraoperative radiation therapy should be used only on women with invasive cancer who are also considered suitable for partial breast irradiation.
- Low-energy X-ray intraoperative radiation therapy should be used only in a clinical trial and only on women with invasive cancer who are considered otherwise suitable for partial breast irradiation.
- Given the persistent risk of cancer coming back in the same breast, all women treated with intraoperative radiation therapy should have regular follow-up exams for at least 10 years after initial diagnosis to screen for any recurrence.
You can learn more about all the radiation treatment options in the Breastcancer.org Radiation Therapy section.