Low-Energy X-Ray Intraoperative Radiation Therapy (Lex-IORT) for Resected Brain Metastases: A Single-Institution Experience

Abstract

Background: Resection followed by local radiation therapy (RT) is the standard of care for symptomatic brain metastases. However, the optimal technique, fractionation scheme and dose are still being debated. Lately, low-energy X-ray intraoperative RT (lex-IORT) has been of increasing interest. Method: Eighteen consecutive patients undergoing BM resection followed by immediate lex-IORT with 16–30 Gy applied to the spherical applicator were retrospectively analyzed. Demographic, RT-specific, radiographic and clinical data were reviewed to evaluate the effectiveness and safety of IORT for BM. Descriptive statistics and Kaplan–Meyer analysis were applied. Results: The mean follow-up time was 10.8 months (range, 0–39 months). The estimated local control (LC), distant brain control (DBC) and overall survival (OS) at 12 months post IORT were 92.9% (95%-CI 79.3–100%), 71.4% (95%-CI 50.2–92.6%) and 58.0% (95%-CI 34.1–81.9%), respectively. Two patients developed radiation necrosis (11.1%) and wound infection (CTCAE grade III); both had additional adjuvant treatment after IORT. For five patients (27.8%), the time to the start or continuation of systemic treatment was ≤15 days and hence shorter than wound healing and adjuvant RT would have required. Conclusion: In accordance with previous series, this study demonstrates the effectiveness and safety of IORT in the management of brain metastases despite the small cohort and the retrospective characteristic of this analysis.

Outcome assessment of intraoperative radiotherapy for brain metastases: results of a prospective observational study with comparative matched-pair analysis

“…By matched pair analysis, we demonstrated comparable long-term survival outcomes of EBRT and IORT. The 1 year-survival rate of 57% reported here is also within the range of previous reports for IORT [ 20 , 22 ]. Meanwhile, despite being marginally different, the matched cohort exhibited outstanding long-term survival.…”

“…The main disadvantage of IORT is a lack of dose modulation options that render certain anatomic conditions challenging. Therefore, it is not surprising that, in line with previous reports [ 20 ], most of the BM treated in this cohort were located either craniofrontal or occipital.…”

“…This is an improvement in comparison to adjuvant SRS or FSRT where RN rates typically range between 8% [ 14 ] to more than 20% [ 49 ], but also to some previous series of IORT patients. While Kahl et al reported 2.5% [ 22 ], Cifarelli et al noted a RN rate of 7% [ 19 ] and Diehl et al of 11.1% [ 20 ]. Of note, the latter also included few patients receiving additional post-surgery stereotactic radiosurgery.…”

“…As an alternative, low-energy intraoperative RT (IORT) has increasingly gained attention in the past years. Initial reports suggest promising LCR [ 19 , 20 ] and a favorable safety profile [ 21 ] with a comparatively lower radiation necrosis (RN) incidence [ 22 ]. Available data are solely based on retrospective single institution experiences, with a radiation oncology focus on dosage and technical aspects of the IORT approach [ 23 , 24 ].…”

Opportunities and Alternatives of Modern Radiation Oncology and Surgery for the Management of Resectable Brain Metastases

“…A second publication, resulting from an international pooled cohort, showed a 1-year 88% LCR in 54 patients with a 7% RN rate [170]. A newly published work adds up to suggesting encouraging safety and control outcomes, similar to all the above-mentioned [184]. It is noteworthy that the reported 12 to 23 min of additional surgical time could help save patient and professional time and reduce hospital visits related to planning and adjuvant treatment delivery.…”