Single-Dose Radiation During Lumpectomy May Equal Postoperative Radiotherapy

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: For women with early breast cancer, a single dose of risk-adapted targeted intraoperative radiotherapy (TARGIT-IORT) delivered during surgery offers comparable long-term local control to a postoperative course of whole-breast external beam radiotherapy (EBRT), the TARGIT-A investigators say. 

“Single dose TARGIT-IORT during lumpectomy should be accessible to healthcare providers and discussed with patients when surgery for breast cancer is being planned”, say Jayant Vaidya, from University College London in the UK, and co-authors in The BMJ. 

The primary outcome of local recurrence-free survival (RFS) or death at 5 years was 2.11% for the 1140 women randomly assigned to undergo TARGIT-IORT for invasive ductal carcinoma up to 3.5 cm in size with clinical N0–N1. 

This did not significantly differ from the 5-year rate of 0.95% for the 1158 women who instead received EBRT over 3–6 weeks and the 1.16 percentage point difference between the treatment arms indicated that the TARGIT-IORT regimen was non-inferior to the conventional radiotherapy arm. This was confirmed by 5-year Kaplan-Meier estimates, which indicated a nonsignificant 1.21 percentage point difference. 

And after a median 8.6 years – and a maximum 18.9 years – of follow-up, the TARGIT-IORT and EBRT arms did not significantly differ in terms of local RFS, invasive local RFS, mastectomy-free survival, distant disease-free survival or overall survival. 

The two treatment arms also had comparable breast cancer mortality rates (65 vs 57 events) but TARGIT-IORT was associated with a significantly lower rate of mortality from other causes than EBRT (45 vs 74 events, hazard ratio=0.59). 

The researchers emphasize that 80% of patients did not require further radiotherapy after TARGIT-IORT and cite earlier studies indicating that both cost and “quality of life and patient reported outcomes such as cosmesis, breast related quality of life and breast pain to be superior with TARGIT-IORT in the first 5 years”. 

This may, in part, be due to many patients living a “considerable distance from the radiotherapy centre” and being able to “avoid the need for daily hospital visits for three to six weeks, which would be required for established radiotherapy techniques”, they suggest. 

Jayant Vaidya et al conclude: “We believe that the long term data presented in this paper, together with many benefits for the patient, provide compelling evidence in favour of TARGIT-IORT as an effective alternative for this large group of patients with early breast cancer who are suitable for breast conservation.” 

Reference  

Vaidya JS, Bulsara M, Baum M, et al. Long term survival and local control outcomes from single dose targeted intraoperative radiotherapy during lumpectomy (TARGIT-IORT) for early breast cancer: TARGIT-A randomised clinical trial. BMJ; 370: m2836 published online 19 August 2020. doi: 10.1136/bmj.m2836