Intraoperative RT matches EBRT for early breast cancer

According to the latest results from randomized trials, a single dose of intraoperative radiation therapy (IORT) resulted in a long-term outcome for early breast cancer comparable to that achieved with conventional external beam radiation therapy (EBRT).

After median follow-up of 8.6 years (up to 19 years), key outcomes including local recurrence-free survival (LRFS), distant disease-free survival (DDFS), and overall survival (including) were significant between treatment groups. There was no difference in OS), or breast cancer mortality. The results were similar to those After 5 years of follow-up In TARGIT-A trial, BMJ..

“The long-term results of this trial were based on the risk-adjusted single-dose TARGIT-IORT [targeted intraoperative radiotherapy]When given during a lumpectomy, it can effectively replace the weeks’ essential use of daily postoperative total breast radiotherapy in breast cancer patients undergoing breast-conserving surgery. Jayant S. of University College London.

“Importantly, 80% of patients did not require additional radiation therapy after TARGIT-IORT,” the researchers said. “In addition, TARGIT-IORT reduced non-breast cancer mortality. The benefit to patients avoiding postoperative radiation therapy appears to be clear.”

The long-term results of TARGIT-A add another chapter to the clinical story that began more than 20 years ago. The authors note that when the TARGIT-A protocol was published in 1999, the concept of limiting radiation therapy to the perimeter of the tumor was poorly evaluated. of Randomized trial only Studies conducted to that point showed inferior results for localized RT.

Patients scheduled for breast-conserving surgery were randomized to immediate risk-adaptive IORT during surgical resection or standard whole-breast irradiation for 3 to 6 weeks. Researchers found that about 20% of patients assigned to IORT received additional EBRT (rather than cross-therapy) using prespecified risk criteria, but did not affect statistical considerations He said.

The primary outcome was noninferiority of 5-year local recurrence with risk-adaptive IORT for EBRT (whole breast radiotherapy). The researchers chose an absolute difference of 2.5% as the definition of noninferiority.

The primary data analysis included 2,298 patients who were randomized. The trial met the key results because the 5-year local recurrence rate was 1.3% for EBRT versus 3.3% for risk-adapted IORT. Although the differences suggested a statistical advantage of EBRT (P= 0.042), the difference did not exceed the inferiority 2.5% margin.

Breast cancer-specific mortality rates (2.6% at IORT vs. 1.9% at EBRT) also did not differ in a 5-year follow-up analysis, with slightly lower overall mortality at IORT (3.9% vs. 5.3%). Patients assigned to the IORT had significantly lower non-breast cancer mortality (1.4% vs. 3.5%, P= 0.0086).

Local recurrence and survival were the key outcomes of the long-term follow-up analysis. With 5-year complete follow-up of all patients, 5-year local recurrence rates were 2.11% for IORT and 0.95% for EBRT, the difference remained within the statistical definition of noninferiority, the researchers said. ..

With additional follow-up, the investigators found no significant differences in the following:

• LRFS: HR 1.13, 95% CI 0.91-1.41

• Survival without mastectomy: HR 0.96, 95% CI 0.78-1.19

• DDFS: HR 0.88, 95% CI 0.69-1.12

• OS: HR 0.82, 95% CI 0.63-1.05

• Breast cancer mortality rate: HR 1.12, 95% CI 0.78-1.60

Mortality from causes other than breast cancer remains significantly lower in the IORT group (HR 0.59, 95% CI 0.40-0.86).

Penny R. Anderson, MD, of the Fox Chase Scanner Center in Philadelphia, achieved major results in five years and, despite longer follow-up, has not gained significant support among U.S. breast cancer specialists .. A person unrelated to research.

“Intraoperative radiation therapy is not commonly used in the United States, not at Fox Chase at all,” Anderson said. MedPage today on mail. “If the facility offers this option to patients, it is for patients with small initial tumors or negative nodes who have negative surgical margins. Ideally, patients with partial breast radiation will not receive this type of radiation. They tend to be good candidates.”