New clinical and biological insights from the international TARGIT-A randomised trial of targeted intraoperative radiotherapy during lumpectomy for breast cancer

Journal article

BACKGROUND: The TARGIT-A trial reported risk-adapted targeted intraoperative radiotherapy (TARGIT-IORT) during lumpectomy for breast cancer to be as effective as whole-breast external beam radiotherapy (EBRT). Here, we present further detailed analyses. METHODS: In total, 2298 women (≥45 years, invasive ductal carcinoma ≤3.5 cm, cN0-N1) were randomised. We investigated the impact of tumour size, grade, ER, PgR, HER2 and lymph node status on local recurrence-free survival, and of local recurrence on distant relapse and mortality. We analysed the predictive factors for recommending supplemental EBRT after TARGIT-IORT as part of the risk-adapted approach, using regression modelling. Non-breast cancer mortality was compared between TARGIT-IORT plus EBRT vs. EBRT. RESULTS: Local recurrence-free survival was no different between TARGIT-IORT and EBRT, in every tumour subgroup. Unlike in the EBRT arm, local recurrence in the TARGIT-IORT arm was not a predictor of a higher risk of distant relapse or death. Our new predictive tool for recommending supplemental EBRT after TARGIT-IORT is at https://targit.org.uk/addrt . Non-breast cancer mortality was significantly lower in the TARGIT-IORT arm, even when patients received supplemental EBRT, HR 0.38 (95% CI 0.17-0.88) P = 0.0091. CONCLUSION: TARGIT-IORT is as effective as EBRT in all subgroups. Local recurrence after TARGIT-IORT, unlike after EBRT, has a good prognosis. TARGIT-IORT might have a beneficial abscopal effect. TRIAL REGISTRATION: ISRCTN34086741 (21/7/2004), NCT00983684 (24/9/2009)

Authors: Vaidya, JS; Bulsara, M; Baum, M; Wenz, F; Massarut, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer Nature [academic journals on nature.com]
• Journal: British Journal of Cancer
• Volume: 125
• Issue: 3
• Pages: 380-389
• Publication date: 2021-05-25
• DOI: 10.1038/s41416-021-01440-8
• EISSN: 1532-1827
• ISSN: 0007-0920
• Language: English
• Keywords: Intraoperative radiotherapy; Surgery; Mastectomy; Medicine; Brachytherapy; External beam radiotherapy; Lumpectomy; Radiation therapy; Breast cancer; Radiology; Oncology; Cancer; Internal medicine