Partial breast irradiation with intraoperative radiotherapy in the ELIOT trial

We congratulate Roberto Orecchia and colleagues 1 Orecchia R Veronesi U Maisonneuve P et al. Intraoperative irradiation for early breast cancer (ELIOT): long-term recurrence and survival outcomes from a single-centre, randomised, phase 3 equivalence trial. Lancet Oncol. 2021; 22: 597-608 Summary Full Text Full Text PDF PubMed Scopus (25) Google Scholar for their Article reporting the long-term outcomes of the ELIOT trial, for which the first publication (with 5-year data) took place in 2013. 2 Veronesi U Orecchia R Maisonneuve P et al. Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol. 2013; 14: 1269-1277 Summary Full Text Full Text PDF PubMed Scopus (531) Google Scholar Reported risk-stratified cumulative incidences of breast cancer recurrence rates were now based on the renewed American Society for Radiation Oncology criteria for partial breast irradiation. 3 Correa C Harris EE Leonardi MC et al. Accelerated partial breast irradiation: executive summary for the update of an ASTRO Evidence-based consensus statement. Pract Radiat Oncol. 2017; 7: 73-79 Summary Full Text Full Text PDF PubMed Scopus (328) Google Scholar For patients defined as cautionary under the American Society for Radiation Oncology criteria (n=182), Orecchia and colleagues 1 Orecchia R Veronesi U Maisonneuve P et al. Intraoperative irradiation for early breast cancer (ELIOT): long-term recurrence and survival outcomes from a single-centre, randomised, phase 3 equivalence trial. Lancet Oncol. 2021; 22: 597-608 Summary Full Text Full Text PDF PubMed Scopus (25) Google Scholar (table 3) report a 15-year breast cancer recurrence rate of 10% (95% CI 6·3–14·7)—surprisingly lower than the 15-year breast cancer recurrence rate in 223 patients defined as suitable (13·1% [95% CI 8·3–19·1]), which was, in turn, unexpectedly high. An explanation for this contradictory observation was not discussed, raising the question of whether target volumes were sufficiently encompassed by tumouricidal doses of 21 Gy (90% isodose) applied by electrons. Appropriate target volumes with full doses of intraoperative electron radiotherapy (21 Gy at the 90% isodose) are generally achieved by use of the correct sizes of tube diameters and electron energies, depending on the tumour-free resection margins. Treatment recommendations (ie, technical prerequisites, dosimetric specifications, and patient selection criteria) were published in European guidelines in 2020. 4 Fastner G Gaisberger C Kaiser J et al. ESTRO IORT Task Force/ACROP recommendations for intraoperative radiation therapy with electrons (IOERT) in breast cancer. Radiother Oncol. 2020; 149: 150-157 Summary Full Text Full Text PDF PubMed Scopus (19) Google Scholar In their first publication, 2 Veronesi U Orecchia R Maisonneuve P et al. Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol. 2013; 14: 1269-1277 Summary Full Text Full Text PDF PubMed Scopus (531) Google Scholar the authors also reported the use of smaller-sized tubes, which might lead to insufficient coverage of a given target volume and which are currently discouraged. At the time of that publication, 2 Veronesi U Orecchia R Maisonneuve P et al. Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol. 2013; 14: 1269-1277 Summary Full Text Full Text PDF PubMed Scopus (531) Google Scholar the rate of true local relapses was already 50% higher than the rate of recurrence outside of the original tumour location, and a sub-group analysis for these results has not been provided with the latest Article. 1 Orecchia R Veronesi U Maisonneuve P et al. Intraoperative irradiation for early breast cancer (ELIOT): long-term recurrence and survival outcomes from a single-centre, randomised, phase 3 equivalence trial. Lancet Oncol. 2021; 22: 597-608 Summary Full Text Full Text PDF PubMed Scopus (25) Google Scholar We strongly encourage Orecchia and colleagues to supply additional information (ie, tube diameters, electron energies, and the percentage of irradiated target tissues receiving 90% of the dose) and to discuss their recurrence analyses as a function of treated volumes. Quality criteria for breast intraoperative electron radiotherapy have been substantially refined since the beginning of the ELIOT study, more than 20 years ago. Partial breast irradiation with intraoperative radiotherapy in the ELIOT trialWe congratulate Roberto Orecchia and colleagues1 for presenting long-term results of partial breast irradiation with electron intraoperative radiotherapy for patients with early breast cancer (the ELIOT trial) in The Lancet Oncology. In this single-centre, randomised phase 3 trial, 1305 women were randomly allocated into two groups to receive a single electron intraoperative radiotherapy dose of 21 Gy or whole-breast irradiation. Higher rates of ipsilateral breast tumour relapse were found in the electron intraoperative radiotherapy group than in the whole-breast irradiation group (15 year recurrence rate: 12·6% vs 2·4%; p<0·0001), without differences in overall survival. Full-Text PDF Partial breast irradiation with intraoperative radiotherapy in the ELIOT trialWe congratulate Roberto Orecchia and colleagues1 for publishing the long-term results of the single-centre, phase 3, randomised, equivalence ELIOT trial, in which 1305 women (aged 48–75 years, with a unicentric tumour ≤2·5 cm in diameter, and node-negative) were randomly assigned to receive a single 21 Gy fraction of electron intraoperative radiotherapy, or whole-breast irradiation over 6 weeks. Higher 15-year rates of local relapse were found in the electron intraoperative radiotherapy group (12·6% vs 2·4%; p<0·0001). Full-Text PDF Partial breast irradiation with intraoperative radiotherapy in the ELIOT trial – Authors' replyWe would like to thank our colleagues for their interest in the updated ELIOT trial.1 By showing a higher local relapse rate in the accelerated partial breast irradiation group, we do not intend to discourage the use of electron intraoperative radiotherapy (ELIOT)—let alone of accelerated partial breast irradiation in general—but rather to underscore the importance of appropriate patient selection. The ELIOT trial has identified a subgroup of patients with a notably low rate of local recurrence after either accelerated partial breast irradiation or whole-breast irradiation. Full-Text PDF Intraoperative irradiation for early breast cancer (ELIOT): long-term recurrence and survival outcomes from a single-centre, randomised, phase 3 equivalence trialThe long-term results of this trial confirmed the higher rate of IBTR in the ELIOT group than in the WBI group, without any differences in overall survival. ELIOT should be offered to selected patients at low-risk of IBTR. Full-Text PDF Partial breast irradiation with intraoperative radiotherapy in the ELIOT trialDescribing the long-term outcomes of the ELIOT trial,1 the authors point out "the possible local side-effects of the [ELIOT] technique (immediate fat necrosis, skin flap-temporary suffering, or late parenchymal fibrosis)", which is an important detail. Full-Text PDF