Resection of supratentorial brain metastases with intraoperative radiotherapy. Is it safe? Analysis and experiences of a single center cohort

Intraoperative radiotherapy after neurosurgical resection of brain metastases as institutional standard treatment- update of the oncological outcome form a single center cohort after 117 procedures

PURPOSE

Stereotactic radiotherapy (SRT) is the predominant method for the irradiation of resection cavities after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50 kV x-rays is an alternative way to irradiate the resection cavity focally. We have already reported the outcome of our first 40 IORT patients treated until 2020. Since then, IORT has become the predominant cavity treatment in our center due to patients´ choice.

METHODS

We retrospectively analyzed the outcomes of all patients who underwent resection of BM and IORT between 2013 and August 2023 at Augsburg University Medical Center (UKA).

RESULTS

We identified 105 patients with 117 resected BM treated with 50 kV x-ray IORT. Median diameter of the resected metastases was 3.1 cm (range 1.3 - 7.0 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including three-monthly MRI of the brain. Mean FU was 14 months, with a median MRI FU for patients alive of nine months. Median overall survival (OS) of all treated patients was 18.2 months (estimated 1-year OS 57.7%). The observed local control (LC) rate of the resection cavity was 90.5% (estimated 1-year LC 84.2%). Distant brain control (DC) was 61.9% (estimated 1-year DC 47.9%). Only 16.2% of all patients needed WBI in the further course of disease. The observed radio necrosis rate was 2.6%.

CONCLUSION

After 117 procedures IORT still appears to be a safe and appealing way to perform cavity RT after neurosurgical resection of BM with low toxicity and excellent LC.

Intraoperative radiotherapy combined with spinal stabilization surgery-a novel treatment strategy for spinal metastases based on a first single-center experiences

INTRODUCTION

Current treatment of spinal metastases (SM) aims on preserving spinal stability, neurological status, and functional status as well as achieving local control. It consists of spinal surgery followed by radiotherapy and/or systemic treatment. Adjuvant therapy usually starts with a delay of a few weeks to prevent wound healing issues. Intraoperative radiotherapy (IORT) has previously been successfully applied during brain tumor, breast and colorectal carcinoma surgery but not in SM, including unstable one, to date. In our case series, we describe the feasibility, morbidity and mortality of a novel treatment protocol for SM combining stabilization surgery with IORT.

METHODS

Single center case series on patients with SM. Single session stabilization by navigated open or percutaneous procedure using a carbon screw-rod system followed by concurrent 50 kV photon-IORT (ZEISS Intrabeam). The IORT probe is placed via a guide canula using navigation, positioning is controlled by IOCT or 3D-fluroscopy enabling RT isodose planning in the OR.

RESULTS

15 (8 female) patients (71 ± 10y) received this treatment between 07/22 and 09/23. Median Spinal Neoplastic Instability Score was 8 [7-10] IQR. Most metastasis were located in the thoracic (n = 11, 73.3%) and the rest in the lumbar (n = 4, 26.7%) spine. 9 (60%) patients received open, 5 (33%) percutaneous stabilization and 1 (7%) decompression only. Mean length of surgery was 157 ± 45 min. Eleven patients had 8 and 3 had 4 screws placed. In 2 patients radiotherapy was not completed due to bending of the guide canula with consecutive abortion of IORT. All other patients received 8 Gy isodoses at mdn. 1.5 cm [1.1-1.9, IQR] depth during 2-6 min. The patients had Epidural Spinal Cord Compression score 1a-3. Seven patients (46.7%) experienced adverse events including 2 surgical site infection (one 65 days after surgery).

CONCLUSION

50 kV photon IORT for SM and consecutive unstable spine needing surgical intervention is safe and feasible and can be a promising technique in selected cases.

Neuro-oncologic Emergencies

OBJECTIVE

Neuro-oncologic emergencies have become more frequent as cancer remains one of the leading causes of death in the United States, second only to heart disease. This article highlights key aspects of epidemiology, diagnosis, and management of acute neurologic complications in primary central nervous system malignancies and systemic cancer, following three thematic classifications: (1) complications that are anatomically or intrinsically tumor-related, (2) complications that are tumor-mediated, and (3) complications that are treatment-related.

LATEST DEVELOPMENTS

The main driver of mortality in patients with brain metastasis is systemic disease progression; however, intracranial hypertension, treatment-resistant seizures, and overall decline due to increased intracranial burden of disease are the main factors underlying neurologic-related deaths. Advances in the understanding of tumor-specific characteristics can better inform risk stratification of neurologic complications. Following standardized grading and management algorithms for neurotoxic syndromes related to newer immunologic therapies is paramount to achieving favorable outcomes.

ESSENTIAL POINTS

Neuro-oncologic emergencies span the boundaries of subspecialties in neurology and require a broad understanding of neuroimmunology, neuronal hyperexcitability, CSF flow dynamics, intracranial compliance, and neuroanatomy.

Multicentric Assessment of Safety and Efficacy of Combinatorial Adjuvant Brain Metastasis Treatment by Intraoperative Radiation Therapy and Immunotherapy

PURPOSE

After surgical resection of brain metastases (BMs), intraoperative radiation therapy (IORT) provides a promising alternative to adjuvant external beam radiation therapy by enabling superior organ-at-risk preservation, reduction of in-hospital times, and timely admission to subsequent systemic treatments, which increasingly comprise novel targeted immunotherapeutic approaches. We sought to assess the safety and efficacy of IORT in combination with immune checkpoint inhibitors (ICIs) and other targeted therapies (TTs).

METHODS AND MATERIALS

In a multicentric approach incorporating individual patient data from 6 international IORT centers, all patients with BMs undergoing IORT were retrospectively assessed for combinatorial treatment with ICIs/TTs and evaluated for toxicity and cumulative rates, including wound dehiscence, radiation necrosis, leptomeningeal spread, local control, distant brain progression (DBP), and estimated overall survival.

RESULTS

In total, 103 lesions with a median diameter of 34 mm receiving IORT combined with immunomodulatory systemic treatment or other TTs were included. The median follow-up was 13.2 (range, 1.2-102.4) months, and the median IORT dose was 25 (range, 18-30) Gy prescribed to the applicator surface. There was 1 grade 3 adverse event related to IORT recorded (2.2%). A 4.9% cumulative radiation necrosis rate was observed. The 1-year local control rate was 98.0%, and the 1-year DBP-free survival rate was 60.0%. Median time to DBP was 5.5 (range, 1.0-18.5) months in the subgroup of patients experiencing DBP, and the cumulative leptomeningeal spread rate was 4.9%. The median estimated overall survival was 26 (range, 1.2 to not reached) months with a 1-year survival rate of 74.0%. Early initiation of immunotherapy/TTs was associated with a nonsignificant trend toward improved DBP rate and overall survival.

CONCLUSIONS

The combination of ICIs/TTs with IORT for resected BMs does not seem to increase toxicity and yields encouraging local control outcomes in the difficult-to-treat subgroup of larger BMs. Time gaps between surgery and systemic treatment could be shortened or avoided. The definitive role of IORT in local control after BM resection will be defined in a prospective trial.

Intraoperative radiotherapy after resection of brain metastases located in the posterior fossa. Analysis of postoperative morbidity and mortality in a single center cohort

INTRODUCTION

In order to improve surgical outcome and accelerate the adjuvant oncologic therapy, intraoperative Radiotherapy (IORT) has become a treatment option in oncologic surgery for various diseases including glioma and brain metastasis (BM). BMs are often located in the cranial posterior fossa (PF) requiring specific surgical considerations due to its complex anatomy. Up until now, data on IORT for BMs is limited and detailed description in the use of IORT for lesions in the PF is lacking. Our aim is to provide more insight into this emerging treatment strategy.

METHODS

We performed a retrospective analysis of patients receiving surgery for BMs and undergoing IORT at our institution. Each patient was discussed at the interdisciplinary tumor board decision before the intervention. Patient characteristics, functional status (Karnofsky Performance Score, KPS) before and after surgery, disease (recursive partitioning analysis, lesion size) and operative parameters were analyzed. Adverse events (AE) were recorded up until 30 days after the intervention and rated according to the Clavien Dindo Rating scale.

RESULTS

Nine patients (5 female) were included. None underwent prior radiotherapy (RT). Mean age was 66 ± 11 years. Preoperative median KPS was 80%. Mean BM diameter was 3.2 ± 0.9 cm. There was no statistically significant deterioration of the functional status after the intervention. Two patients experienced AEs with both of them needing revision surgery.

CONCLUSION

Surgery for BMs with IORT in the PF seems safe and feasible. Further studies are needed to evaluate the influence of IORT on long-term outcome after BM surgery.

Intraoperative or postoperative stereotactic radiotherapy for brain metastases: time to systemic treatment onset and other patient-relevant outcomes

PURPOSE

Intraoperative radiotherapy (IORT) has become a viable treatment option for resectable brain metastases (BMs). As data on local control and radiation necrosis rates are maturing, we focus on meaningful secondary endpoints such as time to next treatment (TTNT), duration of postoperative corticosteroid treatment, and in-hospital time.

METHODS

Patients prospectively recruited within an IORT study registry between November 2020 and June 2023 were compared with consecutive patients receiving adjuvant stereotactic radiotherapy (SRT) of the resection cavity within the same time frame. TTNT was defined as the number of days between BM resection and start of the next extracranial oncological therapy (systemic treatment, surgery, or radiotherapy) for each of the groups.

RESULTS

Of 95 BM patients screened, IORT was feasible in 84 cases (88%) and ultimately performed in 64 (67%). The control collective consisted of 53 SRT patients. There were no relevant differences in clinical baseline features. Mean TTNT (range) was 36 (9 - 94) days for IORT patients versus 52 (11 - 126) days for SRT patients (p = 0.01). Mean duration of postoperative corticosteroid treatment was similar (8 days; p = 0.83), as was mean postoperative in-hospital time (11 versus 12 days; p = 0.97). Mean total in-hospital time for BM treatment (in- and out-patient days) was 11 days for IORT versus 19 days for SRT patients (p < 0.001).

CONCLUSION

IORT for BMs results in faster completion of interdisciplinary treatment when compared to adjuvant SRT, without increasing corticosteroid intake or prolonging in-hospital times. A randomised phase III trial will determine the clinical effects of shorter TTNT.

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

PURPOSE

Intraoperative radiation therapy (IORT) is an emerging alternative to adjuvant stereotactic external beam radiation therapy (EBRT) following resection of brain metastases (BM). Advantages of IORT include an instant prevention of tumor regrowth, optimized dose-sparing of adjacent healthy brain tissue and immediate completion of BM treatment, allowing an earlier admission to subsequent systemic treatments. However, prospective outcome data are limited. We sought to assess long-term outcome of IORT in comparison to EBRT.

METHODS

A total of 35 consecutive patients, prospectively recruited within a study registry, who received IORT following BM resection at a single neuro-oncological center were evaluated for radiation necrosis (RN) incidence rates, local control rates (LCR), distant brain progression (DBP) and overall survival (OS) as long-term outcome parameters. The 1 year-estimated OS and survival rates were compared in a balanced comparative matched-pair analysis to those of our institutional database, encompassing 388 consecutive patients who underwent adjuvant EBRT after BM resection.

RESULTS

The median IORT dose was 30 Gy prescribed to the applicator surface. A 2.9% RN rate was observed. The estimated 1 year-LCR was 97.1% and the 1 year-DBP-free survival 73.5%. Median time to DBP was 6.4 (range 1.7-24) months in the subgroup of patients experiencing intracerebral progression. The median OS was 17.5 (0.5-not reached) months with a 1 year-survival rate of 61.3%, which did not not significantly differ from the comparative cohort (p = 0.55 and p = 0.82, respectively).

CONCLUSION

IORT is a safe and effective fast-track approach following BM resection, with comparable long-term outcomes as adjuvant EBRT.

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

Postsurgical radiotherapy (RT) has been early proven to prevent local tumor recurrence, initially performed with whole brain RT (WBRT). Subsequent to disadvantageous cognitive sequalae for the patient and the broad distribution of modern linear accelerators, focal irradiation of the tumor has omitted WBRT in most cases. In many studies, the effectiveness of local RT of the resection cavity, either as single-fraction stereotactic radiosurgery (SRS) or hypo-fractionated stereotactic RT (hFSRT), has been demonstrated to be effective and safe. However, whereas prospective high-level incidence is still lacking on which dose and fractionation scheme is the best choice for the patient, further ablative techniques have come into play. Neoadjuvant SRS (N-SRS) prior to resection combines straightforward target delineation with an accelerated post-surgical phase, allowing an earlier start of systemic treatment or rehabilitation as indicated. In addition, low-energy intraoperative RT (IORT) on the surgical bed has been introduced as another alternative to external beam RT, offering sterilization of the cavity surface with steep dose gradients towards the healthy brain. This consensus paper summarizes current local treatment strategies for resectable brain metastases regarding available data and patient-centered decision-making.