Intraoperative radiotherapy to treat newly diagnosed solitary brain metastasis: initial experience and long-term outcomes

Stereotactic radiosurgery versus whole-brain radiotherapy for intracranial metastases: A systematic review and meta-analysis

Background

Brain metastasis has a negative influence on the morbidity and mortality of cancer patients. Conventionally, whole-brain radiotherapy (WBRT) was favored as the standard treatment for brain metastases. However, it has been linked to a significant decline in neuro-cognitive function and poor quality of life. Stereotactic radiosurgery (SRS) has recently gained prominence as an alternative modality, considering that it provides targeted high-dose radiation while minimizing adverse effects. This study evaluates the efficacy and safety of SRS versus WBRT in patients with intracranial metastases.

Methods

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, through July 2024, we searched PubMed, Scopus, and Web of Science for articles comparing WBRT and SRS in patients with intracranial metastases. Outcomes included local and distant recurrence, leptomeningeal disease (LMD), and survival. We also used a random-effect model to perform a meta-analysis.

Results

The findings revealed no significant differences in local (risk ratio [RR] = 0.70, 95% confidence interval [CI] [0.46, 1.06]) or distant recurrence rates (RR = 0.83, 95% CI [0.54, 1.28], P = 0.41) between WBRT and SRS. However, SRS was associated with a greater risk of post-radiation LMD (hazard ratio [HR] = 3.09, 95% CI [1.47, 6.49], P = 0.003). Survival rates at 1 year (RR = 1.03, 95% CI [0.83, 1.29], P = 0.76) and 5 years (RR = 0.89, 95% CI [0.39, 2.04], P = 0.78) demonstrated no significant differences.

Conclusion

SRS and WBRT exhibited similar recurrence rates and overall survival (OS) at 1 and 5 years, with WBRT being more effective in managing post-radiation LMD. SRS patients, on the other hand, had longer OS when measured in months.

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 in recurrent IDH-wildtype glioblastoma with gross total resection: A single-center retrospective study

BACKGROUND

Isocitrate dehydrogenase-wildtype (IDHwt) glioblastoma (GBM) is one of the most aggressive primary brain tumors. The recurrence of GBM is almost inevitable. As an adjuvant option to surgery, intraoperative radiotherapy (IORT) is gaining increasing attention in the treatment of glioma. This study is aimed to evaluate the therapeutic efficacy of IORT on recurrent IDHwt GBM.

METHODS

In total, 34 recurrent IDHwt GBM patients who received a second surgery were included in the analysis (17 in the surgery group and 17 in the surgery + IORT group).

RESULTS

The progression-free survival and overall survival after the second surgery were defined as PFS2 and OS2, respectively. The median PFS2 was 7.3 months (95% CI: 6.3-10.5) and 10.6 months (95% CI: 9.3-14.6) for those patients who received surgery and surgery + IORT, respectively. Patients in the surgery + IORT group also had a longer OS2 (12.8 months, 95% CI: 11.4-17.2) than those in the surgery group (9.3 months, 95% CI: 8.9-12.9). The Kaplan-Meier survival curves, analyzed by log-rank test, revealed a statistically significant difference in PFS2 and OS2 between both groups, suggesting that IORT plays an active role in the observed benefits for PFS2 and OS2. The effects of IORT on PFS2 and OS2 were further confirmed by multivariate Cox hazards regression analysis. Two patients in the surgery group developed distant glioma metastases, and no radiation-related complications were observed in the IORT group.

CONCLUSIONS

This study suggests that low-dose IORT may improve the prognosis of recurrent IDHwt GBM patients. Future prospective large-scale studies are needed to validate the efficacy and safety of IORT.

Brain metastasis treatment guidelines: consensus by the Spanish Society of Neurosurgery Tumor Section

Brain metastases are tumors that arise from a tumor cell originated in another organ reaching the brain through the blood. In the brain this tumor cell is capable of growing and invading neighboring tissues, such as the meninges and bone. In most patients a known tumor is present when the brain lesion is diagnosed, although it is possible that the first diagnose is the brain tumor before there is evidence of cancer elsewhere in the body. For this reason, the neurosurgeon must know the management that has shown the greatest benefit for brain metastasis patients, so treatments can be streamlined and optimized. Specifically, in this document, the following topics will be developed: selection of the cancer patient candidate for surgical resection and the role of the neurosurgeon in the multidisciplinary team, the importance of immunohistological and molecular diagnosis, surgical techniques, radiotherapy techniques, treatment updates of chemotherapy and immunotherapy and management algorithms in brain metastases. With this consensus manuscript, the tumor group of the Spanish Society of Neurosurgery (GT-SENEC) exposes the most relevant neurosurgical issues and the fundamental aspects to harmonize multidisciplinary treatment, especially with the medical specialties that are treating or will treat these patients.

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.

Efficacy of Stereotactic Radiosurgery as Single or Combined Therapy for Brain Metastasis: A Systematic Review and Meta-Analysis

To determine the efficacy of stereotactic radiosurgery (SRS) in treating patients with brain metastases (BMs), a network meta-analysis (NMA) of randomized controlled trials (RCTs) and a direct comparison of cohort studies were performed. Relevant literature regarding the effectiveness of SRS alone and in combination with whole-brain radiotherapy (WBRT) and surgery was retrieved using systematic database searches up to April 2019. The patterns of overall survival (OS), one-year OS, progression-free survival (PFS), one-year local brain control (LBC), one-year distant brain control (DBC), neurological death (ND), and complication rate were analyzed. A total of 18 RCTs and 37 cohorts were included in the meta-analysis. Our data revealed that SRS carried a better OS than SRS+WBRT (p= 0.048) and WBRT (p= 0.041). Also, SRS+WBRT demonstrated a significantly improved PFS, LBC, and DBC compared to WBRT alone and SRS alone. Finally, SRS achieved the same LBC as high as surgery, but intracranial relapse occurred considerably more frequently in the absence of WBRT. However, there were not any significant differences in ND and toxicities between SRS and other groups. Therefore, SRS alone may be a better alternative since increased patient survival may outweigh the increased risk of brain tumor recurrence associated with it.

Intraoperative radiotherapy for brain metastases: first-stage results of a single-arm, open-label, phase 2 trial

OBJECTIVE

Focal stereotactic radiosurgery to the surgical cavity lowers local recurrence after resection of brain metastases (BM). To evaluate local control (LC) and brain disease control (BDC) after intraoperative radiotherapy (IORT) for resected BM.

METHODS

Adult patients with completely resected single supratentorial BM were recruited and underwent IORT to the cavity with a prescribed dose of 18 Gy to 1 mm-depth. Primary endpoints were actuarial LC and BDC. Local failure (LF) and distant brain failure (DBF), with death as a competing risk, were estimated. Secondary endpoints were overall survival (OS) and incidence of radiation necrosis (RN). Simon's two-stage design was used and estimated an accrual of 10 patients for the first-stage analysis and a LC higher than 63% to proceed to second stage. We report the final analysis of the first stage.

RESULTS

Between June 2019 to November 2020, 10 patients were accrued. Median clinical and imaging FU was 11.2 and 9.7 months, respectively. Median LC was not reached and median BDC was 5 months. The 6-month and 12-month LC was 87.5%. The 6-month and 12-month BDC was 39% and 13%, respectively. Incidence of LF at 6 and 12 months was 10% and of DBF at 6 and 12 months was 50% and 70%, respectively. Median OS was not reached. The 6-month and 12-month OS was 80%. One patient had asymptomatic RN.

CONCLUSION

IORT for completely resected BM is associated with a potential high local control and low risk of RN, reaching the pre-specified criteria to proceed to second stage and warranting further studies.

Comparison of immunotherapy combined with stereotactic radiotherapy and targeted therapy for patients with brain metastases: A systemic review and meta-analysis

Advances in brain imaging have led to a higher incidence of brain metastases (BM) being diagnosed. Stereotactic radiotherapy (SRS), systemic immunotherapy, and targeted drug therapy are commonly used for treating BM. In this study, we summarized the differences in overall survival (OS) between several treatments alone and in combination. We carried out a systematic literature search on Pubmed, EMBASE, and Cochrane Library. Differences in OS associated with Immune checkpoint inhibitors (ICI) alone versus targeted therapy alone and SRS + ICI or ICI alone were evaluated. This analysis was conducted on 11 studies involving 4,154 patients. The comprehensive results of fixed effect model showed that the OS of SRS + ICI group was longer than that of the ICI group (hazard ratio, 1.72; 95% CI: 1.41-2.11; P = 0.22; I ² = 30%). The combined fixed-effect model showed that the OS time of ICI was longer than that of targeted therapy (hazard ratio, 2.09; 95% CI: 1.37-3.20; P = 0.21; I ² = 35%). The study had a low risk of bias. In conclusion, our analysis confirmed that immunotherapy alone showed a higher OS benefit in BM patients than targeted therapy alone. The total survival time of patients with SRS combined with ICI was higher than that of patients with single ICI.

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

Introduction

Intraoperative Radiotherapy (ioRT) is an emerging treatment option in oncologic surgery for various diseases including intraaxial brain lesions to improve surgical outcome and accelerate the adjuvant oncologic therapy. Despite its use in glioma surgery, the application and data regarding ioRT in the treatment of brain metastases (BMs) is sparse. Here were report the largest series of supratentorial BMs treated with resection and ioRT according to functional outcome and adverse events.

Methods

We performed a retrospective chart review analysis of patients undergoing surgery for BMs following an interdisciplinary tumor board decision in every case with ioRT at our institution. Patient properties, functional status (Karnofsky Performance Score/KPS) before and after surgery as well as oncologic (disease, recursive partitioning analysis, lesion size) and operative parameters were analyzed until hospital discharge. Adverse events (AE) were recorded until 30 days after surgery and rated according to the Clavien Dindo Grading (CDG) scale.

Results

70 patients (40 female) with various oncologic diseases were identified and analyzed. Six underwent prior RT. Mean age was 66 ± 11 years. Preoperative median KPS was 80% with a mean BM volume of 3.2 ± 1.2 cm³. Nine patients (13%) experienced in total 14 AEs, including 2 cases (3%) of postoperative death (CDG5) and 2 with new postoperative epilepsy necessitating additional pharmacotreatment (CDG2). Five patients suffered from new neurologic deficit (CDG1) not needing further surgical or medical treatment. After surgery, the neurological status in 7 patients (10%) deteriorated while it improved in 21 cases (30%). Patients experiencing AEs had longer hospitalization and poorer postoperative KPS mdn. 90 vs. 80%. There was no statistically significant deterioration of the functional status during the immediate postoperative course in the whole patient cohort.

Conclusion

Surgery for supratentorial BMs with ioRT seems safe and feasible. Further studies on the benefit regarding oncologic outcome need to be performed.

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

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.

Stereotactic radiosurgery for post operative brain metastasic surgical cavities: a single institution experience

BACKGROUND

The standard therapy for brain metastasis was surgery combined with whole brain radiotherapy (WBRT). The latter is however, associated with important neurocognitive toxicity. To reduce this toxicity, postoperative stereotactic radiosurgery (SRS) is a promising technique. We assessed the efficacy and the tolerance to postoperative Gamma Knife radiosurgery (GK) on the tumor bed after resection of brain metastases.

METHODS

Between February 2011 and December 2016, following macroscopic complete surgical resection, 64 patients and 65 surgical cavities were treated by GK in our institution. The indication for adjuvant radiosurgery was a multidisciplinary decision. The main assessment criteria considered in this study were local control, intracranial metastasis-free survival (ICMFS), overall survival and toxicity.

RESULTS

Median follow-up: 11.1 months. Median time between surgery and radiosurgery: 35 days. Median dose was 20 Gy prescribed to the 50% isodose line, for a median treated volume of 5.6 cc. Four patients (7%) suffered from local recurrence. Local recurrence-free, intracranial recurrence-free and overall survival at 1 year were 97.5%, 57.6% and 62.4% respectively. In total, 23 patients (41%) suffered from intracranial recurrence outside the tumor bed. In univariate analysis: concomitant GK treatment of multiple lesions and the tumor bed was associated with a decrease in ICMFS (HR = 1.16 [1.005-1.34] p = 0.04). In multivariate analysis: a non-lung primary tumor was significantly associated with a decrease in ICMFS (HR = 8.04 [1.82-35.4] p = 0.006). An increase in performance status (PS) and in the initial number of cerebral metastases significantly reduced overall survival (HR = 5.4 [1.11-26.3] p = 0.037, HR = 2.7 [1.004-7.36] p = 0.049, respectively) and One radiation necrosis histologically proven.

CONCLUSION

Our study confirmed that postoperative GK after resection of cerebral metastases is an efficient and well-tolerated technique, to treat volumes of all sizes (0.8 to 40 cc). Iterative SRS or salvage WBRT can be performed in cases of intracranial relapse, postponing WBRT with its potential side effects.

Benchmarking Safety Indicators of Surgical Treatment of Brain Metastases Combined with Intraoperative Radiotherapy: Results of Prospective Observational Study with Comparative Matched-Pair Analysis

Simple Summary

Patients with brain metastasis (BM) are at advanced stages of metastatic cancer, and surgical resection is often required in order to avoid severe neurologic deficits. After surgery, patients are usually committed to postoperative radiotherapy. In recent years, intraoperative radiotherapy (IORT) has been proposed as an alternative to conventional postsurgical radiation approaches. This possibility has several advantages, e.g., as IORT is administered only once during the surgical procedure, patients do not have to attend several radiotherapy sessions afterward. However, the application of radiation therapy directly into the open brain during surgery might be accompanied by severe perioperative complications and, therefore, might negatively impact the overall benefit. In the present study, we show that patients who underwent surgery for BM combined with IORT do not suffer from elevated levels of perioperative complications compared to patients without IORT. Therefore, IORT constitutes a safe treatment strategy for cancer patients with BM.

Abstract

Intraoperative radiotherapy (IORT) of the operative cavity for surgically treated brain metastasis (BM) has gained increasing prominence with respect to improved local tumor control. However, IORT immediately performed at the time of surgery might be associated with increased levels of perioperative adverse events (PAEs). In the present study, we performed safety metric profiling in patients who had undergone surgery for BM with and without IORT in order to comparatively analyze feasibility of IORT as an adjuvant radiation approach. Between November 2020 and October 2021, 35 patients were surgically treated for BM with IORT at our neuro-oncological center. Perioperative complication profiles were collected in a prospective observational cohort study by means of patient safety indicators (PSIs), hospital-acquired conditions (HACs), and specific cranial-surgery-related complications (CSCs) as high-standard quality metric tools and compared to those of an institutional cohort of 388 patients with BM resection without IORT in a balanced comparative matched-pair analysis. Overall, 4 out of 35 patients (11%) with IORT in the course BM resection suffered from PAEs, accounting for 3 PSIs (9%) and 1 HAC (3%). Balanced matched-pair analysis did not reveal significant differences in the perioperative complication profiles between the cohorts of patients with and without IORT (p = 0.44). Thirty-day mortality rates were 6% for patients with IORT versus 8% for patients without IORT (p = 0.73). The present study demonstrates that IORT constitutes a safe and clinically feasible adjuvant treatment modality in patients undergoing surgical resection of BM.

Early Therapeutic Interventions for Newly Diagnosed Glioblastoma: Rationale and Review of the Literature

PURPOSE OF REVIEW

Glioblastoma is the commonest primary brain cancer in adults whose outcomes are amongst the worst of any cancer. The current treatment pathway comprises surgery and postoperative chemoradiotherapy though unresectable diffusely infiltrative tumour cells remain untreated for several weeks post-diagnosis. Intratumoural heterogeneity combined with increased hypoxia in the postoperative tumour microenvironment potentially decreases the efficacy of adjuvant interventions and fails to prevent early postoperative regrowth, called rapid early progression (REP). In this review, we discuss the clinical implications and biological foundations of post-surgery REP. Subsequently, clinical interventions potentially targeting this phenomenon are reviewed systematically.

RECENT FINDINGS

Early interventions include early systemic chemotherapy, neoadjuvant immunotherapy, local therapies delivered during surgery (including Gliadel wafers, nanoparticles and stem cell therapy) and several radiotherapy techniques. We critically appraise and compare these strategies in terms of their efficacy, toxicity, challenges and potential to prolong survival. Finally, we discuss the most promising strategies that could benefit future glioblastoma patients. There is biological rationale to suggest that early interventions could improve the outcome of glioblastoma patients and they should be investigated in future trials.

Management Strategies for Large Brain Metastases

Brain metastases represent the most common intracranial neoplasm and pose a significant disease burden on the individual and the healthcare system. Although whole brain radiation therapy was historically a first line approach, subsequent research and technological advancements have resulted in a larger armamentarium of strategies for treatment of these patients. While chemotherapeutic options remain limited, surgical resection and stereotactic radiosurgery, as well as their combination therapies, have shifted the paradigms for managing intracranial metastatic disease. Ultimately, no single treatment is shown to be consistently effective across patient groups in terms of overall survival, local and distant control, neurocognitive function, and performance status. However, close consideration of patient and tumor characteristics may help delineate more favorable treatment strategies for individual patients. Here the authors present a review of the recent literature surrounding surgery, whole brain radiation therapy, stereotactic radiosurgery, and combination approaches.

Intraoperative Radiotherapy in Brain Malignancies: Indications and Outcomes in Primary and Metastatic Brain Tumors

Despite the continued controversy over defining an optimal delivery mechanism, the critical role of adjuvant radiation in the management of surgically resected primary and metastatic brain tumors remains one of the universally accepted standards in neuro-oncology. Local disease control still ranks as a significant predictor of survival in both high-grade glioma and treated intracranial metastases with radiation treatment being essential in maximizing tumor control. As with the emergence and eventual acceptance of cranial stereotactic radiosurgery (SRS) following an era dominated by traditional radiotherapy, evidence to support the use of intraoperative radiotherapy (IORT) in brain tumors requiring surgical intervention continues to accumulate. While the clinical trial strategies in treating glioblastoma with IORT involve delivery of a boost of cavitary radiation prior to the planned standard external beam radiation, the use of IORT in metastatic disease offers the potential for dose escalation to the level needed for definitive adjuvant radiation, eliminating the need for additional episodes of care while providing local control equal or superior to that achieved with SRS in a single fraction. In this review, we explore the contemporary clinical data on IORT in the treatment of brain tumors along with a discussion of the unique dosimetric and radiobiological factors inherent in IORT that could account for favorable outcome data beyond those seen in other techniques.

Intraoperative radiotherapy with low-energy x-rays after neurosurgical resection of brain metastases-an Augsburg University Medical Center experience

PURPOSE

External-beam radiotherapy (EBRT) is the predominant method for localized brain radiotherapy (LBRT) after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50-kV x‑rays is an alternative way to focally irradiate the resection cavity after BM surgery, with the option of shortening the overall treatment time and limiting normal tissue irradiation.

METHODS

We retrospectively analyzed the outcomes of all patients who underwent neurosurgical resection of BM and 50-kV x‑ray IORT between 2013 and 2020 at Augsburg University Medical Center.

RESULTS

We identified 40 patients with 44 resected BM treated with 50-kV x‑ray IORT. Median diameter of the resected metastases was 2.8 cm (range 1.5-5.9 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including 3‑monthly MRI of the brain. Mean FU was 14.4 months, with a median MRI FU for alive patients of 12.2 months. Median overall survival (OS) of all treated patients was 26.4 months (estimated 1‑year OS 61.6%). The observed local control (LC) rate of the resection cavity was 88.6% (estimated 1‑year LC 84.3%). Distant brain control (DC) was 47.5% (estimated 1‑year DC 33.5%). Only 25% of all patients needed WBI in the further course of disease. The observed radionecrosis rate was 2.5%.

CONCLUSION

IORT with 50-kV x‑rays is a safe and appealing way to apply LBRT after neurosurgical resection of BM, with low toxicity and excellent LC. Close MRI FU is paramount to detect distant brain failure (DBF) early.

The evolving role of neurosurgery for central nervous system metastases in the era of personalized cancer therapy

Recent therapeutic advances involving the use of systemic targeted treatments and immunotherapeutic agents in patients with advanced cancers have translated into improved survival rates. Despite the emergence of such promising pharmacological therapies and extended survival, the frequency of metastases in the central nervous system has steadily increased. Effective medical and surgical therapies are available for many patients with brain metastases and need to be incorporated into multi-disciplinary care protocols. The role of neurosurgeons is evolving within these multi-disciplinary care teams. Surgical resection of brain metastases can provide immediate relief from neurological symptoms due to large lesions and provides the histopathological diagnosis in cases of no known primary malignancy. In situations where immunotherapy is part of the oncological treatment plan, surgery may be proposed for expeditious relief of edema to remove the need for steroids. In patients with multiple brain metastases and mixed response to therapeutics or radiosurgery, tumour resampling allows tissue analysis for druggable targets or to distinguish radiation effects from progression. Ventriculo-peritoneal shunting may improve quality of life in patients with hydrocephalus associated with leptomeningeal tumour dissemination and may allow for time to administer more therapy thus prolonging overall survival. Addressing the limited efficacy of many oncological drugs for brain metastases due to insufficient blood-brain barrier penetrance, clinical trial protocols in which surgical specimens are analysed after pre-surgical administration of therapeutics offer pharmacodynamic insights. Comprehensive neurosurgical assessment remains an integral element of multi-disciplinary oncological care of patients with brain metastases and is integral to tumour biology research and therapeutic advancement.

Safety and efficacy of INTRABEAM intraoperative radiotherapy for invasive thymoma

Intraoperative radiotherapy (IORT) has been used to treat different residual solid tumors after tumor removal and has shown many advantages over other treatment methods. However, the use of IORT for invasive thymoma has not been reported. Therefore, in this study, we tried to determine the safety and efficacy of INTRABEAM IORT for the treatment of invasive thymoma.Among the patients admitted to our hospital from September to December 2016 who were diagnosed with invasive thymoma, 14 were selected as study subjects. With medical histories taken beforehand, 8 of these patients were diagnosed with Masaoka stage IIA and 6 with Masaoka stage IIB; furthermore, 5 of the patients were diagnosed with myasthenia gravis (MG). INTRABEAM radiation (8-10 Gy, low energy) was delivered to the postoperative tumor bed of each patient during surgery. The intra- and postoperative complications were observed and evaluated, and the improvement in symptoms was assessed. An additional 23 patients with stage II thymoma undergoing radical surgery from April to August 2016 were chosen as the control group.One month after the operation, only 1 patient in the IORT group had cough, increased levels of leucocytes and neutrophils, and pulmonary inflammation on chest computed tomography. Reactive inflammation and pleural effusion in the 2 groups were similar (P > .05). There was no significant difference between the 2 groups in the improvement of myasthenia gravis (P > .05). Postoperative chest computed tomography and routine blood examination at 3 and 12 months showed that all the patients recovered, with normal hemogram levels and no pulmonary fibrosis around the radiation field. In addition, ultrasonic cardiography and electrocardiography demonstrated no significant difference before or after surgery within the IORT group. At the end of the follow-up, all the patients were alive, no relapse or remote metastasis was observed in the IORT group, and 2 inpatients in the control group had experienced relapse at 24 and 26 months. There was a significant difference in disease-free survival between the 2 groups (P = .00).It is safe to administer low-energy INTRABEAM IORT at a dose of approximately 10 Gy in patients with stage II invasive thymoma. INTRABEAM IORT does not significantly increase operation- or radiation-related complications and has no significant effect on vital organs such as the lungs and heart. Its long-term efficacy is worth expecting.

Intraoperative radiotherapy as an immediate adjuvant treatment of rectal cancer due to limited access to external-beam radiotherapy

BACKGROUND

Neoadjuvant external-beam radiotherapy (EBRT) with concomitant chemotherapy is the current standard-of-care for locally-advanced rectal cancer. Intraoperative radiotherapy (IORT) is to date only recommended for pelvic recurrences or incompletely resectable tumors. We here report on patients with stage II/III rectal cancer that were treated with IORT in a regional Russian university center due to limited access to EBRT.

METHODS

We retrospectively analyzed data from patients that were diagnosed with locally-advanced rectal cancer and underwent surgery from December 2012 to October 2016 at a regional oncological center in Russia (Krasnodar). During this period, access to EBRT was limited due to a temporary lack of a sufficient number of EBRT facilities. Patients unable to travel to a distant radiotherapy site received IORT alone, those that could travel received neoadjuvant external beam (chemo-) radiotherapy. Factors of interest were tumor stage, tumor differentiation, resection status, surgery type and neoadjuvant or adjuvant chemotherapy. We assessed local progression-free survival (L-PFS), PFS and overall survival (OS).

RESULTS

A total of 172 patients were included in this analysis. Of those, 92 (53.5%) were treated with IORT alone (median dose: 15 Gy [8.4-17 Gy]) and 80 (46.5%) received both neoadjuvant EBRT (median dose: 50.4 Gy [40-50.4 Gy]) and IORT (median dose: 15 Gy [15-17 Gy]). The median age was 65 years [33-82]. The median follow-up was 23 months [0-63 months]. The incidence of toxicity was low in both groups with an overall complication rate of 5.4%. Local PFS at 4 years was comparable with 59.4% in the IORT group and 65.4% in the IORT/EBRT group (p = 0.70). Similarly, there was no difference in OS or PFS (p = 0.66, p = 0.51, respectively).

CONCLUSIONS

IORT is a valuable option for patients with locally-advanced rectal cancer in the absence of access to EBRT.

The American Brachytherapy Society consensus statement on intraoperative radiation therapy

PURPOSE

Although radiation therapy has traditionally been delivered with external beam or brachytherapy, intraoperative radiation therapy (IORT) represents an alternative that may shorten the course of therapy, reduce toxicities, and improve patient satisfaction while potentially lowering the cost of care. At this time, there are limited evidence-based guidelines to assist clinicians with patient selection for IORT. As such, the American Brachytherapy Society presents a consensus statement on the use of IORT.

METHODS

Physicians and physicists with expertise in intraoperative radiation created a site-directed guideline for appropriate patient selection and utilization of IORT.

RESULTS

Several IORT techniques exist including radionuclide-based high-dose-rate, low-dose-rate, electron, and low-energy electronic. In breast cancer, IORT as monotherapy should only be used on prospective studies. IORT can be considered in the treatment of sarcomas with close/positive margins or recurrent sarcomas. IORT can be considered in conjunction with external beam radiotherapy for retroperitoneal sarcomas. IORT can be considered for colorectal malignancies with concern for positive margins and in the setting of recurrent gynecologic cancers. For thoracic, head and neck, and central nervous system malignancies, utilization of IORT should be evaluated on a case-by-case basis.

CONCLUSIONS

The present guidelines provide clinicians with a summary of current data regarding IORT by treatment site and guidelines for the appropriate patient selection and safe utilization of the technique. High-dose-rate, low-dose-rate brachytherapy methods are appropriate when IORT is to be delivered as are electron and low-energy based on the clinical scenario.

Intraoperative radiotherapy (IORT) for surgically resected brain metastases: outcome analysis of an international cooperative study

BACKGROUND AND OBJECTIVE

The ideal delivery of radiation to the surgical cavity of brain metastases (BMs) remains the subject of debate. Risks of local failure (LF) and radiation necrosis (RN) have prompted a reappraisal of the timing and/or modality of this critical component of BM management. IORT delivered at the time of resection for BMs requiring surgery offers the potential for improved local control (LC) afforded by the elimination of delay in time to initiation of radiation following surgery, decreased uncertainty in target delineation, and the possibility of dose escalation beyond that seen in stereotactic radiosurgery (SRS). This study provides a retrospective analysis with identification of potential predictors of outcomes.

METHODS

Retrospective data was collected on patients treated with IORT immediately following surgical resection of BMs at three institutions according to the approval of individual IRBs. All patients were treated with 50kV portable linear accelerator using spherical applicators ranging from 1.5 to 4.0 cm. Statistical analyses were performed using IBM SPSS with endpoints of LC, DBC, incidence of RN, and overall survival (OS) and p < 0.05 considered significant.

RESULTS

54 patients were treated with IORT with a median age of 64 years. The most common primary diagnosis was non-small cell lung cancer (40%) with the most common location in the frontal lobe (38%). Median follow-up was 7.2 months and 1-year LC, DBC, and OS were 88%, 58%, and 73%, respectively. LMD was identified in 2 patients (3%) and RN present in 4 patients (7%). The only predictor of LC was extent of resection with 1-year LC of 94% for GTR versus 62% for STR (p = 0.049).

CONCLUSIONS

IORT is a safe and effective means of delivering adjuvant radiation to the BM resection cavities with high rates of LC and low incidence of RN. Further studies are warranted directly comparing LC outcomes to SRS.

A Novel Radiotherapy Approach for Keloids with Intrabeam

Background

Keloids are hard nodules or plaques formed by excessive proliferation of connective tissue. Radiotherapy, widely used in various benign and malignant skin diseases, is an effective treatment for keloids. This work evaluates Intrabeam photon radiotherapy in the management of keloids.

Methods

Fourteen patients who have undergone Intrabeam radiotherapy for a total of 15 sites of keloids were followed up. Twelve cases were first onset and the other two had recurrent diseases. Thirteen patients underwent surgical resection of keloids before radiotherapy. One relapsing patient received only 2 rounds of radiation therapy as she could not be reoperated. Radiotherapy was divided into 2 sessions on days 0 and 3 after surgery. The dose was 4 or 5 Gy each time for 3 min 14 s to 12 min 1 s. In addition, we compared our data to the recurrence of keloids in fourteen patients who had previously been exposed to electron beam using conventional accelerators.

Results

We analyzed the treatment for adverse reactions and recurrence. In the Intrabeam group, one patient developed superficial skin ulcers a month after treatment. No one experienced wound rupture, bleeding, infection, skin contractures, or obvious hyperpigmentation. None of the fourteen cases showed any recurrence so far after on median 22.5 months of follow-up. Five patients in the electron beam group relapsed 3 to 10 months after treatment.

Conclusion

Here, Intrabeam photon radiotherapy was shown to be an effective treatment for keloid scars and it is therefore recommended for management of this disease.

Longitudinal MRI findings in patients with newly diagnosed glioblastoma after intraoperative radiotherapy

BACKGROUND AND PURPOSE

Post-radiation treatment effects (pseudoprogression/radionecrosis) may bias MRI-based tumor response evaluation. To understand these changes specifically after high doses of radiotherapy, we analyzed MRIs of patients enrolled in the INTRAGO study (NCT02104882), a phase I/II dose-escalation trial of intraoperative radiotherapy (20-40 Gy) in glioblastoma.

METHODS

INTRAGO patients were evaluated and compared to control patients who received standard therapy with focus on contrast enhancement patterns/volume, T2 lesion volume, and mean rCBV.

RESULTS

Overall, 11/15 (73.3%) INTRAGO patients (median age 60 years) were included. Distant failure was observed in 7/11 (63.6%) patients, local tumor recurrence in one patient (9.1%). On the first follow-up MRI all but one patient demonstrated enhancement of varying patterns around the resection cavity which were: in 2/11 (18.2%) patients thin and linear, in 7/11 (63.6%) combined linear and nodular, and in 1/11 (9.1%) voluminous, indistinct, and mesh-like. In the course of treatment, most patients developed the latter two patterns (8/11 [72.7%]). INTRAGO patients demonstrated more often combined linear and nodular and/or voluminous, indistinct, mesh-like components (8/11 [72.7%]) in comparison to control patients (3/12 [25%], P = 0.02). INTRAGO patients demonstrated significantly increasing enhancing lesion (P = 0.001) and T2 lesion volumes (P < 0.001) in the longitudinal non-parametric analysis in comparison to the control group. rCBV showed no significant differences between both groups.

CONCLUSIONS

High doses of radiotherapy to the tumor cavity result in more pronounced enhancement patterns/volumes and T2 lesion volumes. These results will be useful for the response evaluation of patients exposed to high doses of radiotherapy in future studies.

Feasibility of dose escalation using intraoperative radiotherapy following resection of large brain metastases compared to post-operative stereotactic radiosurgery

BACKGROUND AND PURPOSE

Post-operative SRS (stereotactic radiosurgery) for large brain metastases is challenged by risks of radiation necrosis that limit SRS dose. Intraoperative radiotherapy (IORT) is a potential alternative, however standard dose recommendations are lacking.

METHODS AND MATERIALS

Twenty consecutive brain metastases treated with post-operative SRS were retrospectively compared to IORT plans generated for 10-30 Gy in 1 fraction to 0-5 mm by estimating the applicator size and distance from critical organs using pre-operative and post-operative MRI. Additionally, 7 consecutive patients treated with IORT 30 Gy to surface were compared to retrospectively generated SRS plans using the post-operative MRI to 15-20 Gy and 30 Gy in 1 fraction marginal dose.

RESULTS

For the 20 resection cavities treated with SRS and retrospectively compared to IORT, IORT from 10 to 30Gy resulted in lower or not significantly different doses to the optic apparatus and brainstem. Comparatively for the 7 patients treated with IORT 30 Gy to retrospective SRS plans to standard 15-20 Gy and 30 Gy marginal dose, IORT resulted in significantly lower doses to the optic apparatus and brainstem. At a median follow-up of 6.2 months, 86% of patients treated with surgery and IORT achieved local control and 0% developed radiographic or symptomatic radiation necrosis.

CONCLUSIONS

Critical organ dosimetry for IORT remains generally lower than that achieved with single fraction SRS following resection of large brain metastases. We recommend 30 Gy to surface as the preferred prescription, consistent with the dose recommendation for IORT in glioblastoma used in the ongoing INTRAGO-II phase-III trial. Early clinical outcomes appear promising for surgery and IORT.

Stereotactic radiosurgery (SRS) alone versus whole brain radiotherapy plus SRS in patients with 1 to 4 brain metastases from non-small cell lung cancer stratified by the graded prognostic assessment: A meta-analysis (PRISMA) of randomized control trials

BACKGROUND

The present study aims to assess the therapeutic effect of whole brain radiotherapy (WBRT) for brain metastases from non-small cell lung cancer stratified by graded prognostic assessment (GPA) through meta-analysis.

METHODS

The Cochrane Library, PubMed, Ovid (Elsevier) were retrieved. The included randomized controlled trials (RCT) were evaluated, and the statistical analysis was performed using RevMan 5.3 software. Cochrane handbook was applied to evaluate the methodological quality. Statistical significance was considered as P < .05.

RESULTS

There were 2 randomized control trials identified eligible for the meta-analysis. Stereotactic radiosurgery (SRS)+WBRT did not significantly improved overall survival (OS) in 2 subgroups. (GPA <2: HR, 0.93; 95% confidence interval [CI], 0.61-1.40; P = .71), (GPA ≥2: HR, 1.28; 95% CI, 0.58-2.80; P = .54). The use of SRS+WBRT significantly extended brain tumor recurrence (BTR) free time in both subgroups (GPA <2: HR, 5.46; 95% CI: 2.09-14.22; P = .0005), (GPA ≥2: HR, 4.24; 95% CI: 2.24-8.04; P < .00001). The meta-analysis showed salvage therapy was more frequent among the SRS-alone in 2 subgroups (GPA <2: RR, 5.83; 95% CI: 1.47-23.06; P = .01), (GPA ≥2: RR, 2.53; 95% CI: 1.30-4.93; P = .006). The rate of grade 3 or 4 late radiation toxic effects was similar in 2 subgroups between SRS and SRS+WBRT CONCLUSIONS:: Because there are few studies to meet inclusion criteria, we cannot include more researches. The results of this analysis must be carefully interpreted in view of the unclear risk of bias in inclusion in the study. This meta-analysis of 2 randomized trails indicated that the combined treatment group did not show a survival benefit over SRS alone. However, SRS+WBRT improved BTR free time in the subgroup both GPA <2 and GPA ≥2 with the similar grade 3 or 4 late radiation toxicities.

Intraoperative radiotherapy for the treatment of thyroid cancer: a pilot study

We preliminarily evaluated the clinical feasibility and efficacy of intraoperative radiotherapy in patients with thyroid carcinoma. Nine thyroid cancer patients received intraoperative radiotherapy using an Intrabeam system. The dose was 3-4 Gy and the irradiation time ranged from 1 min 32 s to 7 min 33s. One case was a primary thyroid carcinoma, while the other cases were recurrent disease. Adverse effects, recurrence and survival were analyzed. In one patient, poorly differentiated thyroid carcinoma recurred 5 months after treatment, one patient developed a postoperative tracheal skin fistula, and one patient developed a wound infection. Because the affected areas were treated with both surgical resection and then radiotherapy, it is difficult to know which of those led to the adverse effects. Nonetheless, our results indicate that intraoperative radiotherapy can relieve the symptoms associated with thyroid cancer and improve the quality of life for these patients. It thus appears feasible to treat thyroid cancer patients with intraoperative radiotherapy.

American College of Radiology-American Brachytherapy Society practice parameter for electronically generated low-energy radiation sources

BACKGROUND

This collaborative practice parameter technical standard has been created between the American College of Radiology and American Brachytherapy Society to guide the usage of electronically generated low energy radiation sources (ELSs). It refers to the use of electronic X-ray sources with peak voltages up to 120 kVp to deliver therapeutic radiation therapy.

MAIN FINDINGS

The parameter provides a guideline for utilizing ELS, including patient selection and consent, treatment planning, and delivery processes. The parameter reviews the published clinical data with regard to ELS results in skin, breast, and other cancers.

CONCLUSIONS

This technical standard recommends appropriate qualifications of the involved personnel. The parameter reviews the technical issues relating to equipment specifications as well as patient and personnel safety. Regarding suggestions for educational programs with regard to this parameter,it is suggested that the training level for clinicians be equivalent to that for other radiation therapies. It also suggests that ELS must be done using the same standards of quality and safety as those in place for other forms of radiation therapy.

Immunotherapy Combined with Large Fractions of Radiotherapy: Stereotactic Radiosurgery for Brain Metastases-Implications for Intraoperative Radiotherapy after Resection

Brain metastases (BM) affect approximately a third of all cancer patients with systemic disease. Treatment options include surgery, whole-brain radiotherapy, or stereotactic radiosurgery (SRS) while chemotherapy has only limited activity. In cases where patients undergo resection before irradiation, intraoperative radiotherapy (IORT) to the tumor bed may be an alternative modality, which would eliminate the repopulation of residual tumor cells between surgery and postoperative radiotherapy. Accumulating evidence has shown that high single doses of ionizing radiation can be highly efficient in eliciting a broad spectrum of local, regional, and systemic tumor-directed immune reactions. Furthermore, immune checkpoint blockade (ICB) has proven effective in treating antigenic BM and, thus, combining IORT with ICB might be a promising approach. However, it is not known if a low number of residual tumor cells in the tumor bed after resection is sufficient to act as an immunizing event opening the gate for ICB therapies in the brain. Because immunological data on tumor bed irradiation after resection are lacking, a rationale for combining IORT with ICB must be based on mechanistic insight from experimental models and clinical studies on unresected tumors. The purpose of the present review is to examine the mechanisms by which large radiation doses as applied in SRS and IORT enhance antitumor immune activity. Clinical studies on IORT for brain tumors, and on combined treatment of SRS and ICB for unresected BM, are used to assess the safety, efficacy, and immunogenicity of IORT plus ICB and to suggest an optimal treatment sequence.

Stereotactic radiosurgery versus whole-brain radiotherapy after intracranial metastasis resection: a systematic review and meta-analysis

Background

In patients with one to three brain metastases who undergo resection, options for post-operative treatments include whole-brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS) of the resection cavity. In this meta-analysis, we sought to compare the efficacy of each post-operative radiation modality with respect to tumor recurrence and survival.

Methods

Pubmed, Embase and Cochrane databases were searched through June 2016 for cohort studies reporting outcomes of SRS or WBRT after metastasis resection. Pooled effect estimates were calculated using fixed-effect and random-effect models for local recurrence, distant recurrence, and overall survival.

Results

Eight retrospective cohort studies with 646 patients (238 with SRS versus 408 with WBRT) were included in the analysis. Comparing SRS to WBRT, the overall crude risk ratio using the fixed-effect model was 0.59 for local recurrence (95%-CI: 0.32–1.09, I²: 3.35%, P-heterogeneity = 0.36, 3 studies), 1.09 for distant recurrence (95%-CI: 0.74–1.60, I²: 50.5%, P-heterogeneity = 0.13; 3 studies), and 2.99 for leptomeningeal disease (95% CI 1.55–5.76; I²: 14.4% p-heterogeneity: 0.28; 2 studies). For the same comparison, the risk ratio for median overall survival was 0.47 (95% CI: 0.41–0.54; I²: 79.1%, P-heterogeneity < 0.01; 4 studies) in a fixed-effect model, but was no longer significant (0.63; 95%-CI: 0.40–1.00) in a random-effect model. SRS was associated with a lower risk of leukoencephalopathy (RR: 0.15, 95% CI: 0.07–0.33, 1 study), yet with a higher risk of radiation-necrosis (RR: 19.4, 95% CI: 1.21–310, 1 study).

Conclusion

Based on retrospective cohort studies, the results of this study suggest that SRS of the resection cavity may offer comparable survival and similar local and distant control as adjuvant WBRT, yet may be associated with a higher risk for developing leptomeningeal disease. Future research on SRS should focus on achieving a better understanding of the various factors that may favor SRS over WBRT.