Intraoperative radiotherapy for gliomas

Efficacy and Safety of Intraoperative Radiotherapy for High-Grade Gliomas: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

High-grade gliomas (HGGs) are aggressive tumors of the central nervous system that cause significant morbidity and mortality. Despite advances in surgery and radiation therapy (RT), HGG still has a high incidence of recurrence and treatment failure. Intraoperative radiotherapy (IORT) has emerged as a promising therapeutic approach to achieve local tumor control while sparing normal brain tissue from radiation-induced damage.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines to evaluate the use of IORT for HGG. Eligible studies were included based on specific criteria, and data were independently extracted. Outcomes of interest included complications, IORT failure, survival rates at 12 and 24 months, and mortality.

RESULTS

Sixteen studies comprising 436 patients were included. The overall complication rate after IORT was 17%, with significant heterogeneity observed. The IORT failure rate was 77%, while the survival rates at 12 and 24 months were 74% and 24%, respectively. The mortality rate was 62%.

CONCLUSION

This meta-analysis suggests that IORT may be a promising adjuvant treatment for selected patients with HGG. Despite the high rate of complications and treatment failures, the survival outcomes were comparable or even superior to conventional methods. However, the limitations of the study, such as the lack of a control group and small sample sizes, warrant further investigation through prospective randomized controlled trials to better understand the specific patient populations that may benefit most from IORT. However, the limitations of the study, such as the lack of a control group and small sample sizes, warrant further investigation. Notably, the ongoing RP3 trial (NCT02685605) is currently underway, with the aim of providing a more comprehensive understanding of IORT. Moreover, future research should focus on managing complications associated with IORT to improve its safety and efficacy in treating HGG.

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.

Application of intraoperative radiotherapy for malignant glioma

Malignant glioma is characterized by rapid tumor cell proliferation and high recurrence risk. In terms of its treatment, the therapeutic effects of maximum resection and postoperative radiotherapy with adjuvant chemotherapy as well as many other new therapeutic techniques such as antiangiogenic therapy and immunotherapy remain poor. Glioma recurrence, especially local recurrence, is an important reason of glioma treatment failure. Intraoperative radiotherapy (IORT) enables exclusion of radiation-sensitive normal tissue from the radiation field in operation and then the application of a single high-dose precision irradiation to the residual tumor or tumor bed. IORT has great application potential in the control of local recurrence of malignant tumors. This paper thus aims to review the current status and prospects of IORT's application in malignant glioma treatment.

Surgical Treatment of Glioblastoma: State-of-the-Art and Future Trends

Glioblastoma (GBM) is a highly aggressive disease and is associated with poor prognosis despite treatment advances in recent years. Surgical resection of tumor remains the main therapeutic option when approaching these patients, especially when combined with adjuvant radiochemotherapy. In the present study, we conducted a comprehensive literature review on the state-of-the-art and future trends of the surgical treatment of GBM, emphasizing topics that have been the object of recent study.

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.

[Repetitive resection and intrasurgery radiation therapy of brain malignant gliomas: history of question and modern state of problem]

Numerous studies have shown that the degree of primary resection of malignant gliomas of the brain (MG) directly correlates with rates of relapse-free and overall patient survival. Currently, there is no unequivocal opinion regarding the indications and effectiveness of repeated resection in relapse of MG after combined treatment. Surgical intervention, taking into account the pathomorphological features of these tumors, is not healing and should be supplemented with certain methods of adjuvant treatment. The article reviews and analyzes publications devoted to repeated resection and various methods of intraoperative radiation therapy in the treatment of MG. Based on the analysis, the authors of the article came to the conclusion that it is advisable to start their own research on the use of intraoperative balloon brachytherapy in the treatment of recurrent MG based on modern technological solutions.

Repeat Resection and Intraoperative Radiotherapy for Malignant Gliomas of the Brain: A History and Review of Current Techniques

The degree of primary resection of malignant brain gliomas (MBGs) has correlated positively with progression-free and overall survival. The indications for surgery and reoperation in MBG relapse remain controversial. Surgery will not be curative and should be followed by adjuvant treatment. We reviewed the reported studies with respect to repeat resection and the various methods of intraoperative radiotherapy for MBGs from the initial experience with high-energy linear accelerators in Japan to modern, integrated brachytherapy solutions using solid and balloon applicators. Because of the findings from our review, we have begun to research into the use of intraoperative balloon brachytherapy for recurrent MBGs.

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.

First Experience of Intraoperative Radiation Therapy in Cerebral High Grade Glioma in Iran: A Report of Three Cases and Literature Review

Introduction:

Among the high grade cerebral gliomas, Glioblastoma multiform for instance, would be the main pattern of local recurrence causes clinical deterioration and deaths. This has observed 2 - 3 cm upon the initial lesion. During the period of 2 - 4 weeks post-surgery, remaining tumor cells have re-grown until radiochemotherapy has initiated. So it has seemed clear that improved local control could hopefully translate into improved survival. As a matter of fact, mass reduction has insufficiently achieved in almost every case of GBM as that the tumor cell number has not fallen below a “threshold” that tumor control might achieve by the host immune system.

Intraoperative Radiation therapy has been one of those add-on therapies, which has performed during or directly after resection and cleared the tumor cavity from microscopically remaining cells.

Although IORT has presented a novel and feasible principle, the method faced a number of technical and geometrical errors and limitations, which has decreased its potential in the reports of previous studies. Examples could be mentioned as incomplete target volume coverage that seemed as the greatest influence on survival, due to irradiation with an inadequate electron cone size, due to angle errors, or inadequately low energies. In contrast to the previously used forward-beaming electron cones, spherical irradiation sources were specifically attractive in brain tumor IORT, even in post resection cavities with normal complex shapes.

Case Presentation:

We have been reporting 3 cases of high grade gliomas, one recurrent GBM, one primary glioma grade III, and the last one recurrent Rhabdoid GBM, which have been fulfilling our entrance criteria of IORT procedure, by using spherical applicators, which has been increasingly discussed in recent studies.

Conclusions:

It was the first experience of intraoperative radiation therapy for cerebral malignant tumours in Iran. Finally, we had a brief overview on the past and present IORT strategies in the treatment of GBM.

INTRAGO: intraoperative radiotherapy in glioblastoma multiforme—a phase I/II dose escalation study

BACKGROUND

Glioblastoma multiforme (GBM) is the most frequent primary malignant brain tumor in adults. Despite multimodal therapies, almost all GBM recur within a narrow margin around the initial resected lesion. Thus, novel therapeutic intensification strategies must target both, the population of dispersed tumor cells around the cavity and the postoperative microenvironment. Intraoperative radiotherapy (IORT) is a pragmatic and effective approach to sterilize the margins from persistent tumor cells, abrogate post-injury proliferative stimuli and to bridge the therapeutic gap between surgery and radiochemotherapy. Therefore, we have set up INTRAGO, a phase I/II dose-escalation study to evaluate the safety and tolerability of IORT added to standard therapy in newly diagnosed GBM. In contrast to previous approaches, the study involves the application of isotropic low-energy (kV) x-rays delivered by spherical applicators, providing optimal irradiation properties to the resection cavity.

METHODS/DESIGN

INTRAGO includes patients aged 50 years or older with a Karnofsky performance status of at least 50% and a histologically confirmed (frozen sections) supratentorial GBM. Safety and tolerability (i.e., the maximum tolerated dose, MTD) will be assessed using a classical 3 + 3 dose-escalation design. Dose-limiting toxicities (DLT) are wound healing deficits or infections requiring surgical intervention, IORT-related cerebral bleeding or ischemia, symptomatic brain necrosis requiring surgical intervention and early termination of external beam radiotherapy (before the envisaged dose of 60 Gy) due to radiotoxicity. Secondary end points are progression-free and overall survival.

TRIAL REGISTRATION

The study is registered with clinicaltrials.gov, number: NCT02104882 (Registration Date: 03/26/2014).

Intra-operative electron beam radiotherapy for newly diagnosed and recurrent malignant gliomas: feasibility and long-term outcomes

INTRODUCTION

Intra-operative electron beam radiotherapy (IOERT) is an alternative to dose escalation for the treatment of central nervous system tumors. The objective of this study was to describe the feasibility and long-term outcomes of IOERT in the treatment of primary and recurrent gliomas.

MATERIALS AND METHODS

From January 1992 through December 2002, all patients treated with IOERT at the Hospital San Francisco de Asis, Madrid/Spain were retrospectively reviewed. The selection criteria included patients with superficial tumors, KPS >70 % and lesions <6 cm. Irradiation was administered in one section. The prescribed dose considered the amount of post-resection residual tumor, previous radiotherapy and the tolerance level of brain structures exposed to IOERT.

RESULTS

There were 17 patients (53 %) with newly diagnosed malignant brain gliomas and 15 patients with recurrent tumors. The delivered dose varied from 8 to 20 Gy (median 12.5 Gy) for primary and from 8 to 16 Gy (median 10 Gy) for recurrent tumors. The median overall survival for the entire cohort was 13 months (14 and 10.4 months for the primary and recurrent, respectively). Three patients presented with radionecrosis, one patient with osteomyelitis at the craniotomy bone flap, one with intracerebral hemorrhage, and another patient experienced a pulmonary embolism.

CONCLUSIONS

IOERT is a feasible technique and can be viewed as a tool in the treatment of newly diagnosed or recurrent brain gliomas.

Intraoperative radiation therapy (IORT) for previously untreated malignant gliomas

BACKGROUND

Intraoperative radiation therapy (IORT) is one of the methods used to deliver a large single dose to the tumor tissue while reducing the exposure of normal surrounding tissue. However, the usefulness of intraoperative electron therapy for malignant gliomas has not been established.

METHODS

During the period from 1987 to 1997, 32 patients with malignant gliomas were treated with IORT. The histological diagnoses were anaplastic astrocytoma in 11 patients and glioblastoma in 21 patients. Therapy consisted of surgical resection and intraoperative electron therapy using a dose of 12--15 Gy (median, 15 Gy). The patients later underwent postoperative external radiation therapy (EXRT) with a median total dose of 60 Gy. Each of the 32 patients treated with IORT was randomly matched with patients who had been treated with postoperative EXRT alone (control). Patients were matched according to histological grade, age, extent of tumor removal, and tumor location.

RESULTS

In the anaplastic astrocytoma group, the one-, two- and five-year survival rates were 81%, 51% and 15%, respectively in the IORT patients and 54%, 43% and 21%, respectively in the control patients. In the glioblastoma group, one-, two- and five-year survival rates were 63%, 26% and 0%, respectively in the IORT patients and 70%, 18% and 6%, respectively in the control patients. There was no significant difference between survival rates in the IORT patients and control patients in either the anaplastic astrocytoma group or glioblastoma group.

CONCLUSIONS

IORT dose not improve survival of patients with malignant gliomas compared to that of patients who have received EXRT alone.

Postoperative radiotherapy of astrocytomas

Astrocytomas account for the majority of primary brain tumors. Low-grade tumors are slowly growing tumors with relatively long overall survival. However, a high percentage of these tumors transform to more malignant, high-grade tumors. High-grade gliomas (anaplastic astrocytomas and glioblastoma multiforme) have a poor prognosis. Treatment options are capable of prolonging the natural history of the disease, but the long-term survival is poor. This review discusses the different postoperative treatment options and the prognostic factors in low- and high-grade astrocytomas.

[Value of radiosurgery in first-line therapy of glioblastoma multiforme. The Heidelberg experience and review of the literature]

AIM

To describe the clinical results and the feasibility of a phase II dose escalation study of small boost target volumes with a radiosurgical technique in patients with positive early postoperative MRI scans.

PATIENTS AND METHOD

Since 1986, 35 patients were treated within a concept for first line therapy. Including criteria were residual tumor < or = 5 cm and Karnofsky performance score > or = 70. The mean age was 54.5 years. The treatment concept included an operation for reduction of tumor volume and a postoperative irradiation. The postoperative irradiation was divided in 2 parts: first, a hyperfractionated (1.8 Gy single dose twice a day, 54 Gy total dose) irradiation was performed containing the tumor and the edema with a 2 cm safety margin. Secondly, a radiosurgical boost dose was delivered. The target volume of this radiosurgery was the contrast enhancing residual tumor in early postoperative MRI scans. The median boost dose was 15 Gy. Survival curves were calculated according to the Kaplan-Meier method. Quality of life was evaluated using objective criteria such as neurological findings, frequency of seizures and steroid medication.

RESULTS

The median survival calculated from the time of diagnosis was 10.1 months. The 1- and 2-year survival rate were 35% and 6%, respectively. Young age tended to longer survival, patients younger than 53 years had a median survival of 10.4 months whereas patients older than 53 years showed a median survival of 9.2 months. The mean value of the boost volume was 22 cm3. Patients with smaller volumes had a median survival of 10.1 months and patients with bigger volumes showed a median survival of 9.9 months, 4.5 months after therapy, 75% of the patients showed improved or stable quality of life.

CONCLUSION

The feasibility of a radiosurgically delivered boost dose after postoperative irradiation could be demonstrated. The observed survival rate is comparable to the survival rates reported in the literature. Whether or not the radiosurgery after postoperative irradiation is able to prolong survival can only be evaluated in a randomized phase III trial.