Oncological outcome, postoperative complications, and mammographic changes after intraoperative radiotherapy with electrons (IOERT) as a boost in a large single‐institution cohort of breast cancer patients

Abstract

Advantages of using intraoperative radiotherapy with electrons (IOERT) as a boosting modality in breast‐conserving therapy include the direct visualization of the tumor bed, a reduced skin dose, and patient convenience. We report oncological outcome, postoperative complication rate, and mammographic changes on follow‐up imaging in women treated at our institution with IOERT as a boost modality in breast‐conserving therapy for early‐stage breast carcinoma. Between January 2007 and June 2018, 763 consecutive patients were enrolled. During breast‐conserving surgery, an IOERT boost of 9 Gy was applied, followed by whole breast irradiation (WBI). At a median follow‐up of 62.2 months (range: 0.5‐135), 13 in‐breast recurrences were observed, yielding a local tumor control rate of 98.4% at 5 years. In multivariable analysis, high tumor grading was predictive for local recurrence (HR = 5.6; 95%CI: 1.19‐26.2). A total of 27 (3.5%) patients developed any kind of postoperative complication. None of the tumor characteristics nor any of the IOERT technical parameters were predictive for development of a postoperative complication. On follow‐up imaging, 145 patients with mammographic changes BIRADS score ≥3 were found of which 50.3% required a biopsy. Only 17 patients had positive biopsies; none of the IOERT parameters were predictive for false‐positive imaging. A 9 Gy IOERT boost combined with postoperative WBI provided outstanding local control rates, was well‐tolerated, with limited postoperative complications. However, radiologists must be aware of a presumable higher prevalence of mammographic changes after IORT as a boost.

Combined Ultrahypofractionated Whole-Breast Irradiation and IORT-Boost: A Safety and Feasibility Analysis

“…Conventionally fractionated WBI (50 Gy in 5 weeks) combined with IORT photon boost was shown to be a standard alternative to other boost techniques [ 29 ]. Moderate hypofractionation WBI (40.05 Gy in 3 weeks) combined with an IORT boost has been confirmed to be safe and feasible using both electrons [ 30 , 31 , 32 , 33 ] and photons [ 15 , 16 , 34 , 35 ]. Our pioneering experience has shown that the combination of immediate IORT plus moderate HWBI is accompanied by favorable results in relation to chronic toxicity and aesthetic results, both in patients with early and locally advanced disease [ 15 , 16 ].…”

“…In our opinion, IORT boost is an excellent treatment when using moderate hypofractionation radiotherapy and is therefore worthy of being combined with an ultrafractionation WBI protocol that produces similar toxicity figures to the moderate hypofractionation protocols [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”

Comparison of mammography and ultrasound findings in the follow-up of patients with breast cancer treated with segmental mastectomy followed by intraoperative electron radiotherapy versus external whole breast radiotherapy

“…There are only a few articles in the literature about imaging findings in patients treated with IORT. 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 Most of these studies are more than 10 years old and have been performed by a few groups involved in the early clinical trials comparing IORT and WBRT. A limited number of findings have been evaluated, and conflicting results were reported.…”

“…There are only a few reports on the radiological findings in patients treated with IORT. 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 Some of them have reported that postoperative changes in mammography and ultrasound (US) are more pronounced in patients treated with IORT compared with those treated conventionally with WBRT. 7 , 8 , 9 , 11 , 13 However, radiological findings, especially sonographic results, after IORT are not well documented.…”

Intraoperative Radiotherapy as a Tumour-Bed Boost Combined with Whole Breast Irradiation Versus Conventional Radiotherapy in Patients with Early-Stage Breast Cancer: A Systematic Review and Meta-analysis

“…Many single-arm studies have demonstrated the efficacy and safety of IORT boost+WBI; [33][34][35][36][37][38][39][40][41][42][43] however, comparative studies on IORT boost+WBI and conventional radiotherapy are still lacking. Through a search of major databases, we screened nine comparative studies of IORT boost+WBI versus conventional radiotherapy, with varying results.…”