ASTRO Updates Partial-Breast Radiation Guidelines
The American Society for Radiation Oncology (ASTRO) updated its guidelines on partial-breast radiation after lumpectomy based on the results of several large studies comparing partial-breast radiation and whole-breast radiation for early-stage breast cancer and DCIS, which found no difference in recurrence (the cancer coming back), cancer-free survival, or overall survival.
The guidelines were published online on Nov. 14, 2023, by the journal Practical Radiation Oncology. Read “Partial Breast Irradiation for Patients With Early-Stage Invasive Breast Cancer or Ductal Carcinoma In Situ: An ASTRO Clinical Practice Guideline.”
What is partial-breast radiation?
Partial-breast radiation gives a larger dose of radiation over a shorter time period to only the part of the breast where the cancer was, rather than the whole breast.
Partial-breast radiation may be given using two techniques:
External beam partial-breast radiation uses a machine called a linear accelerator to aim a beam of radiation at the area affected by cancer. There are two common types:
Three-dimensional conformal radiation therapy, or 3DCRT, uses targeting information so the radiation beams conform to the shape of the area where the cancer was.
Intensity-modulated radiation therapy, or IMRT, is a more advanced version of 3DCRT that allows the radiation oncologist to vary the dose of radiation given to different areas.
Brachytherapy or internal partial-breast radiation uses several small tubes (called multi-catheter brachytherapy) or a single larger device that looks like a balloon with a tube attached to it (called balloon catheter or applicator brachytherapy). The small tubes or balloon are sewn under the skin in the area where the cancer was. A machine places small pieces of radioactive material, called seeds, into the tubes or balloon to deliver the radiation.
Both types of brachytherapy treatments are usually done as outpatient procedures, twice a day, for five days.
About the guidelines
The 2023 guidelines on partial-breast radiation were developed by an expert panel of radiation, medical, and surgical oncologists; a medical physicist; and a patient representative.
The panel reviewed studies comparing partial-breast and whole-breast radiation published up until June 30, 2022.
Partial-breast radiation is strongly recommended for people ages 40 and older diagnosed with early-stage, node-negative (no cancer in the lymph nodes) breast cancer if the cancer is:
Partial-breast radiation is conditionally recommended for people diagnosed with early-stage breast cancer if the cancer is:
grade 3
estrogen receptor-negative
between 2 and 3 centimeters in size
Partial-breast radiation is not recommended for people diagnosed with early-breast cancer with any of the following characteristics:
HER2-positive and not being treated with an anti-HER2 medicine
node-positive (cancer is found in the lymph nodes)
positive surgical margins
Partial-breast radiation also is not recommended for people younger than 40 or people with a known BRCA1 or BRCA2 mutation.
Partial-breast radiation is strongly recommended for people ages 40 and older diagnosed with DCIS that is:
low-to-intermediate grade
2 centimeters or smaller in size
Partial-breast radiation is conditionally recommended for people diagnosed with DCIS that is high grade or between 2 and 3 centimeters in size. The panel noted that partial-breast radiation may not be appropriate for DCIS that has both of these characteristics.
Partial-breast radiation is not recommended for DCIS with positive surgical margins, or for DCIS in a person who is younger than 40 or has a known BRCA1 or BRCA2 mutation.
The panel strongly recommended the following ways to deliver partial-breast radiation for either early-stage breast cancer or DCIS:
3D conformal radiation therapy
intensity-modulated radiation therapy
multi-catheter brachytherapy
The panel conditionally recommended balloon catheter or applicator brachytherapy for early-stage breast cancer or DCIS.
The panel said electron intraoperative partial-breast radiation therapy was not recommended for people diagnosed with early-stage breast cancer, unless they were part of a clinical trial.
The panel also said kilovoltage intraoperative partial-breast radiation therapy alone – without whole-breast radiation – was not recommended, unless it was part of a clinical trial.
A Gray is the measure of a dose of radiation therapy.
The panel strongly recommended the following radiation dose schedules for partial-breast radiation for early-stage breast cancer or DCIS.
30 Gray given in five doses once a day on non-consecutive days within two weeks
40.05 Gray given in 15 doses once a day over three weeks
30.1 Gray given in seven doses twice a day
32 Gray given in eight doses twice a day
34 Gray given in 10 doses twice a day
50 Gray given as 1.6 to 1.8 Gray per hour for pulsed-dose brachytherapy
Pulsed-dose brachytherapy uses a stronger radiation source and delivers radiation in short bursts of 10 to 30 minutes each hour.
“There have been more than 10,000 women included in these randomized controlled trials, with 10 years of follow-up showing equivalency in tumor control between partial-breast and whole-breast radiation for appropriately selected patients,” Simona Shaitelman, MD, EdM, vice chair of the guideline task force and professor of breast radiation oncology at the University of Texas MD Anderson Cancer Center, said in a statement. “These data should be driving a change in practice, and partial-breast radiation should be a larger part of the dialogue when we consult with patients on decisions about how best to treat their early-stage breast cancer.”
What this means for you
The updated recommendations say that many people diagnosed with early-stage, estrogen receptor-positive, node-negative breast cancer or DCIS are eligible for partial-breast radiation, rather than whole-breast.
Standard whole-breast radiation can mean daily appointments for three to seven weeks, depending on the radiation dose schedule. In many cases, partial-breast radiation can be done in fewer treatments, so it may save both time and money.
If you’ve been diagnosed with DCIS or early-stage breast cancer with a low risk of recurrence, you may want to talk to your doctor about these new guidelines and ask if partial-breast radiation makes sense for your unique situation.
— Last updated on March 9, 2024 at 9:21 PM