
==== Front
Breast
Breast
The Breast : Official Journal of the European Society of Mastology
0960-9776
1532-3080
Elsevier

S0960-9776(24)00118-8
10.1016/j.breast.2024.103787
103787
Correspondence
Meta-analysis of intraoperative electron radiation therapy for partial breast irradiation in early breast cancer
Maisonneuve Patrick patrick.maisonneuve@ieo.it
⁎
Division of Epidemiology and Biostatistics, IEO European Institute of Oncology IRCCS, Via Ripamonti 435, 20141, Milan, Italy
Orecchia Roberto
IEO European Institute of Oncology IRCCS, Milan, Italy
⁎ Corresponding author. patrick.maisonneuve@ieo.it
15 8 2024
10 2024
15 8 2024
77 10378711 7 2024
18 7 2024
9 8 2024
© 2024 Published by Elsevier Ltd.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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pmcTo the Editor,

We read with interest Aristei et al.’s [1] review on intraoperative electron radiation therapy (IOeRT) in early breast cancer. They identified 18 studies (2010–2013) reporting on patient outcomes after IOeRT and calculated pooled proportions of various events, such as ipsilateral breast tumors recurrence (IBTR). However, they did not consider the influence of length of follow-up in the different studies, which directly affects the proportions of events observed as studies with longer follow-up reported higher proportion of events. There also seem to be inconsistencies in how new IBTRs were handled across the different studies. A more informative approach would be calculating annual event rates by dividing event proportions by the mean follow-up duration. Such analysis reveals a pooled annual IBTR rate of 0.76 % (95%CI 0.50–1.03) with significant heterogeneity across studies. Notably, the highest IBTR rate (2.14 %/year) in Jacobs' study [2] is double that observed in the IEO trial (0.92 %/year) [3], despite higher proportion of IBTR in the latest study. Furthermore, Aristei et al.'s conclusion that phase I/II/retrospective and prospective studies showed lower IBTR rates compared to the IEO trial is inaccurate. When considering follow-up duration, IBTR rate from the IEO's phase III randomized trial [3] falls within the range of the other studies.

Funding

This work was partially supported by the 10.13039/501100003196 Italian Ministry of Health with Ricerca Corrente and 5 per 1000.

CRediT authorship contribution statement

Patrick Maisonneuve: Writing – review & editing, Writing – original draft, Formal analysis. Roberto Orecchia: Writing – review & editing.

Declaration of competing interest

We declare no competing interests.
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References

1 Aristei C. Camilli F. Epifani V. Borghesi S. Palumbo I. Bini V. Poortmans P. A systematic review and meta-analysis of intraoperative electron radiation therapy delivered with a dedicated mobile linac for partial breast irradiation in early breast cancer Breast 76 2024 Jun 4 103759 10.1016/j.breast.2024.103759
2 Jacobs D.H.M. Mast M.E. Horeweg N. Speijer G. Petoukhova A.L. Straver M. Accelerated partial breast irradiation using external beam or intraoperative electron radiation therapy: 5-year oncological outcomes of a prospective cohort study Int J Radiat Oncol Biol Phys 113 3 2022 570 581 10.1016/j.ijrobp.2022.03.010 35301990
3 Orecchia R. Veronesi U. Maisonneuve P. Galimberti V.E. Lazzari R. Veronesi P. Intraoperative irradiation for early breast cancer (ELIOT): long-term recurrence and survival outcomes from a single-centre, randomised, phase 3 equivalence trial Lancet Oncol 22 5 2021 597 608 10.1016/S1470-204521 33845035
