As reported in JAMA Oncology by Jayant S. Vaidya, MBBS, PhD, and colleagues, the phase III TARGIT-A trial showed that delayed second-procedure targeted intraoperative radiotherapy (TARGIT-IORT) was not noninferior to whole-breast external-beam radiotherapy (EBRT) in preventing local recurrence of early breast cancer. However, no significant differences in mastectomy-free survival, distant disease–free survival, or overall survival were observed between groups during longer-term follow-up.
Jayant S. Vaidya, MBBS, PhD
The noninferiority trial, initiated in 2004, included 1,153 patients from sites in nine countries aged 45 or older with invasive ductal breast carcinoma < 3.5 cm treated with breast conservation. Patients were randomly assigned to receive delayed TARGIT-IORT (n = 581) or conventional EBRT (n = 572) after tumor excision, with delayed TARGIT-IORT being given in a single dose as a second procedure by reopening the lumpectomy wound.
The database for the long-term analysis was locked in July 2019. The primary endpoint was local recurrence with a noninferiority margin of 2.5%.
At 5-year follow-up, local recurrence rates were 3.96% in the TARGIT-IORT group vs 1.05% in the EBRT group, yielding a difference of 2.9% with an upper 90% confidence interval of 4.4% (crossing the noninferiority margin of 2.5%).
After a median follow-up of 9 years, there were no significant differences between the EBRT group and the TARGIT-IORT group in local recurrence-free survival (hazard ratio [HR] = 0.75, P = .052), invasive local recurrence–free survival (HR = 0.75, P = .051), mastectomy-free survival (HR = 0.88, P = .38), distant disease–free survival (HR = 1.00, P = .98), breast cancer mortality (HR = 0.81, P = .50), other-cause mortality (HR = 1.02, P = .89), or overall survival (HR = 0.96, P = .80).
The investigators concluded, “These long-term data show that despite an increase in the number of local recurrences with delayed TARGIT-IORT, there was no statistically significant decrease in mastectomy-free survival, distant disease–free survival, or overall survival.”
Dr. Vaidya, of the Division of Surgery and Interventional Science, University College London, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was funded by UCLH Charities, NIHR Health Technology Assessment Programme, Ninewells Cancer Campaign, National Health and Medical Research Council, and German Federal Ministry of Education and Research. For full disclosures of the study authors, visit jamanetwork.com.