Targeted intraoperative radiotherapy an effective alternative to EBRT for early breast cancer

Single-dose targeted intraoperative radiotherapy during lumpectomy (TARGIT-IORT) for early breast cancer appears to be a good alternative to external beam radiotherapy (EBRT), demonstrating similar long-term efficacy for cancer control and lower nonbreast cancer mortality, according to a study.

“TARGIT-IORT should be discussed with eligible patients when breast conserving surgery is planned,” the researchers said.

A total of 2,298 women aged 45 years with invasive ductal carcinoma up to 3.5 cm in size, cN0-N1, were eligible for breast conservation and randomly assigned before lumpectomy to either risk adapted TARGIT-IORT (n=1,140) or EBRT (n=1,158). The trial was performed in 32 centres in 10 countries (ie, UK, US, Australia, Canada, and Europe).

TARGIT-IORT was given immediately after lumpectomy under the same anaesthetic and was the only radiotherapy for most patients (around 80 percent). On the other hand, EBRT consisted of a standard daily fractionated course (3–6 weeks) of whole breast radiotherapy. The former was supplemented by the latter in about 20 percent of the patients when postoperative histopathology found unsuspected higher risk factors.

TARGIT-IORT was noninferior to EBRT, as shown by its 2.11-percent local recurrence risk at 5-year complete follow-up relative to 0.95 percent for EBRT (difference, 1.16 percent, 90 percent confidence interval [CI], 0.32–1.99). There were 13 additional recurrences reported (24/1,140 vs 11/1,158) but 14 fewer deaths (42/1,140 vs 56/1,158) for TARGIT-IORT compared with EBRT in the first 5 years. [BMJ 2020;370:m2836]

Over a median follow-up of 8.6 years (maximum, 18.90 years; interquartile range, 7.0–10.6 years), no statistically significant difference was observed between the two treatments for the following: local recurrence-free survival (hazard ratio [HR], 1.13, 95 percent CI, 0.91–1.41; p=0.28), mastectomy-free survival (HR, 0.96, 95 percent CI, 0.78–1.19; p=0.74), distant disease-free survival (HR, 0.88, 95 percent CI, 0.69–1.12; p=0.30), overall survival (HR, 0.82, 95 percent CI, 0.63–1.05; p=0.13), and breast cancer mortality (HR, 1.12, 95 percent CI, 0.78–1.60; p=0.54).

Of note, mortality for causes other than breast cancer was markedly lower for TARGIT-IORT (HR, 0.59, 95 percent CI, 0.40–0.86; p=0.005).

“[F]ormal studies have also reported quality of life (QOL) and patient-reported outcomes, such as cosmesis, breast-related QOL, and breast pain, to be superior with TARGIT-IORT in the first 5 years,” the researchers said. “Additionally, patients prefer this approach even when faced with a potentially higher local recurrence risk.” [Breast Cancer Res Treat 2014;143:135-140; Radiat Oncol 2014;9:33; Arch Gynecol Obstet 2019;299:1121-1130; Breast 2012;21:46-49; Radiat Oncol 2013;8:9; Breast Cancer Res Treat 2013;140:519-525; Int J Radiat Oncol Biol Phys 2016;96:55-64]

The researchers also stressed the importance of patient preference in choosing which approach is right for them, based on several factors including side effects, convenience, effectiveness, and personal cost.

“To allow a truly informed patient to make the choice between a risk adapted TARGIT-IORT policy and conventional EBRT, we need to supply the data using absolute numbers in an easily accessible and comprehensible way,” they said.

“Ultimately, the treatment patients receive should be their choice, and they should be provided with the data in a format which is transparent, straightforward, and easily understood,” they added.