Ultra-targeted accelerated partial breast irradiation using TARGIT – a cautionary note

Accelerated partial breast irradiation (APBI) is an abbreviated radiotherapy course delivered to the tissue surrounding the excision cavity. It is under intense clinical investigation as a therapeutic approach for low-risk early-stage breast cancers. Phase II studies of APBI using multicatheter brachytherapy or externalbeam radiotherapy show high local-control rates at 7–12 years median follow up. These studies highlight the long natural history of the low-risk early-stage breast cancers for which APBI is being proposed. It therefore seemed prudent to wait for the 5–10 year follow-up data on ~16,000 women enrolled in seven randomised controlled trials comparing APBI with whole-breast irradiation to make definitive conclusions on the safety and efficacy of APBI and to establish the clinical, pathological or technical contexts where caution should be exercised with different APBI techniques. However, the investigators of one of these trials, the TARGIT trial, thought otherwise. In their report, the TARGIT investigators state that their trial “provides robust andmature evidence... showing that targeted intraoperative radiotherapy is safe,” and concluded that, “for