The free updated clinical practice statement, titled “Accelerated Partial Breast Irradiation: Executive summary for the update of an ASTRO Evidence-Based Consensus Statement,” was published in Practical Radiation Oncology and updates the 2009 ASTRO consensus statement for APBI.
Drawing on recent clinical evidence showing that more patients could benefit from this accelerated therapy, the new guideline lowers the age gap considered suitable to receive APBI, includes patients with low-risk ductal carcinoma in situ (DCIS), and provides directions for the use of intraoperative radiation therapy (IORT) for partial breast irradiation.
The guideline now recommends taking into account the following factors when considering APBI outside clinical trials:
- Patients older than 50 years old can now be considered for APBI; patients from 40 to 49 years old can be considered with caution; and patients younger than 40 not meeting the pathologic criteria should not be considered suitable. The previous practice statement recommended the age gaps to be 60 or older; ages 50-59; younger than 50, respectively.
- Low-risk DCIS patients can be now considered suitable if they meet all low-risk DCIS criteria. The original guideline excluded DCIS patients from the suitable group.
- Surgical margins remain unchanged. Patients are suitable if surgical margins are negative by less than 2 mm, cautionary if margins are close or less than 2 mm, and not suitable if margins are positive.
Based on clinical trial results, the guideline also recommend the use of IORT according to the following:
- Patients must receive counseling from their physicians if their risk of ipsilateral breast tumor recurrence (IBTR) is higher with IORT versus whole breast irradiation (WBI).
- Electron beam IORT should be given only to patients with invasive cancer who are considered suitable for partial breast irradiation.
- Low-energy x-ray IORT should be used only in a prospective registry or in a clinical trial, and restricted to women with invasive cancer who are considered otherwise suitable for partial breast irradiation.
- Given the risk of IBTR over time, all patients receiving IORT should undergo routine follow-up for at least 10 years to monitor for tumor recurrence.
Radiation therapy (RT) is commonly used to treat early-stage breast cancer after breast-conserving surgery to lower the chances of recurrence or metastasis. In these specific cases, radiation therapy is generally administered as WBI through external beams for several weeks.
APBI is an innovative, targeted alternative that delivers radiation directly to the tissue. This approach to RT reportedly reduces treatment time and limits adverse effects, particularly those affecting the heart and lungs.
Since it was first introduced in the late 1990s, only about 75,000 women have received APBI in the United States.
A panel of eight specialists, including radiation and medical oncologists and IORT experts, developed the new guideline after looking at studies published starting in mid-2008, including 419 abstracts and 44 articles meeting inclusion criteria.
“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,” Jay R. Harris, MD, FASTRO, chair of the task force that developed and evaluated the guideline and professor of radiation oncology at Dana-Farber Cancer Institute, said in a press release.
“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,” he said.