Combined salvage therapies for recurrent glioblastoma multiforme: evaluation of an interdisciplinary treatment algorithm

Brachytherapy is an effective and safe salvage option for re-irradiation in recurrent glioblastoma (rGBM): A systematic review

PURPOSE

To evaluate the clinical efficacy and toxicity of brachytherapy as a salvage therapy for patients with recurrent glioblastoma (rGBM).

METHODS AND MATERIALS

We searched the PubMed, Embase, and Cochrane libraries from its inception to June 2023, for eligible studies in which patients underwent brachytherapy for rGBM. Outcomes of interest were mOS, mPFS, OS, PFS, and adverse events (AEs). For individual clinical survival outcomes and common AEs, weighted-mean descriptive statistics were calculated as a summary measure using study sample size as the weight. The calculation formula is as follows: weighted-mean = Σwx/Σw (w is the sample size and x is the outcome).

RESULTS

This review included 29 studies with a total of 1202 rGBM patients, including 22 retrospective and 7 prospective studies. The results showed that from the time of brachytherapy, the mOS and mPFS were 6.8 to 24.4 months and 3.7 to 11.7 months. The OS of 6 months, 1 year, 18 months, 2 years, and 3 years after brachytherapy were 58.3 % to 85.2 % (weighted-mean 76.2 %), 26 % to 66 % (weighted-mean 41.9 %), 20 % to 37 % (weighted-mean 27.6 %), 11 % to 23 % (weighted-mean 14.8 %), and 8 % to 15 % (weighted-mean 12.1 %), respectively. The PFS of 6 months and 1 year after brachytherapy were 26.7 % to 86 % (weighted-mean 53.4 %) and 14 % to 81 % (weighted-mean 24.1 %). Most patients with rGBM will experience treatment failure again during the follow-up period, mainly local (10.7 % to 79.4 %) or marginal(3.6 % to 22.2 %) recurrence, followed by distant failure (6.7 % to 57.7 %). Although therapeutic AEs had not been uniformly reported, the overall toxicity rate was considered to be low. The common AEs reported included progressive neurologic deterioration, seizures, CSF leak, brain necrosis, hemorrhage, and infection/meningitis, with a weighted-mean incidence of 1.9 %, 2.4 %, 4.1 %, 5.4 %, 2.1 %, and 3.8 %, respectively.

CONCLUSIONS

The evidence summarized above, albeit mostly level III, suggests that brachytherapy has acceptable safety and good post-treatment clinical efficacy for selected patients with rGBM. Well-designed, high-quality, large-sample randomized controlled and prospective studies are needed to further validate these findings.

Clinical Uncertainty and Equipoise in the Management of Recurrent Glioblastoma

BACKGROUND

A significant proportion of glioblastoma (GBM) patients are considered for repeat resection, but evidence regarding best management remains elusive. Our aim was to measure the degree of clinical uncertainty regarding reoperation for patients with recurrent GBM.

METHODS

We first performed a systematic review of agreement studies examining the question of repeat resection for recurrent GBM. An electronic portfolio of 37 pathologically confirmed recurrent GBM patients including pertinent magnetic resonance images and clinical information was assembled. To measure clinical uncertainty, 26 neurosurgeons from various countries, training backgrounds, and years' experience were asked to select best management (repeat surgery, other nonsurgical management, or conservative), confidence in recommended management, and whether they would include the patient in a randomized trial comparing surgery with nonsurgical options. Agreement was evaluated using κ statistics.

RESULTS

The literature review did not reveal previous agreement studies examining the question. In our study, agreement regarding best management of recurrent GBM was slight, even when management options were dichotomized (repeat surgery vs. other options; κ=0.198 [95% confidence interval: 0.133-0.276]). Country of practice, years' experience, and training background did not change results. Disagreement and clinical uncertainty were more pronounced within clinicians with (κ=0.167 [0.055-0.314]) than clinicians without neuro-oncology fellowship training (κ=0.601 [0.556-0.646]). A majority (51%) of responders were willing to include the patient in a randomized trial comparing repeat surgery with nonsurgical alternatives in 26/37 (69%) of cases.

CONCLUSION

There is sufficient uncertainty and equipoise regarding the question of reoperation for patients with recurrent glioblastoma to support the need for a randomized controlled trial.

Patterns of recurrence and outcomes of glioblastoma multiforme treated with chemoradiation and adjuvant temozolomide

OBJECTIVES

To assess the patterns of failure and prognostic factors in Brazilian patients with glioblastoma multiforme (GBM) treated with radiotherapy (RT) and concurrent and adjuvant temozolomide (TMZ).

METHODS

Patients with diagnosed GBM post-resection received postoperative RT. TMZ was administered concurrently at 75 mg/m2/day for 28 consecutive days and adjuvant therapy at 150-200 mg/m2/day for 5 days every 28 days. Radiographic failure was defined as any new T1-enhancing lesion or biopsy-confirmed progressive enhancement inside of the radiation field. When possible, patients with recurrence were salvaged with metronomic TMZ, either in combination with a local treatment or alone (surgery or re-irradiation). Several prognostic factors were evaluated for overall survival (OS). Univariate and multivariate analyses were performed to identify significant factors. A p-value <0.05 was considered significant.

RESULTS

This study included 50 patients. The median follow-up time was 21 months. The median RT dose was 60 Gy and all patients received concomitant TMZ. During follow-up, 41 (83.6%) failures were observed, including 34 (83%) in-field, 4 (9.7%) marginal, and 3 (7.3%) distant failures. Metronomic TMZ was used as salvage treatment in 22 (44%) cases and in combination with local treatment in 12 (24%) cases. The median OS and progression-free survival times for the entire cohort were 17 and 9 months, respectively. In univariate analysis, the following factors were significant for better OS: maximal surgical resection (p=0.03), Karnofsky Performance Score (KPS)>70 at diagnosis (p=0.01), metronomic TMZ treatment (p=0.038), recursive partitioning analysis class III (p=0.03), and time to failure >9 months (p=0.0001). In multivariate analysis, the following factors remained significant for better OS: metronomic TMZ (p=0.01) and time to failure >9 months (p=0.0001).

CONCLUSION

The median OS of Brazilian patients with GBM treated with RT and TMZ was satisfactory. Although TMZ therapy has become the standard of care for patients with newly diagnosed GBM, the recurrence rate is extremely high. Metronomic TMZ as salvage treatment improved survival in these patients.

Multimodal treatment for local recurrent malignant gliomas: Resurgery and/or reirradiation followed by chemotherapy

The therapeutic management of recurrent malignant gliomas (MGs) is not determined. Therefore, the efficacy of a multimodal approach and a combination systemic therapy was investigated. A retrospective analysis of 26 MGs patients at first relapse treated with multimodal therapy (chemotherapy plus surgery and/or reirradiation) or chemotherapy alone was performed. Second-line chemotherapy consisted of fotemustine (FTM) in combination with bevacizumab (BEV) (cFTM/BEV) or followed by third-line BEV (sFTM/BEV). Subgroup analyses were performed. Multimodal therapy provided a higher overall response rate (ORR) (73 vs. 47%), disease control rate (DCR) (82 vs. 67%), median progression-free survival (mPFS) (11 vs. 7 months; P=0.08) and median overall survival (mOS) (13 vs. 8 months; P=0.04) compared with chemotherapy. Concomitant FTM/BEV resulted in higher ORR (84 vs. 36%), DCR (92 vs. 57%), mPFS (10 vs. 5 months; P=0.22) and mOS (11 vs. 5.2 months; P=0.15) compared with sFTM/BEV. Methylated patients did not experience additional survival benefits with multimodality treatment but had higher mPFS (10 vs 7.1 months; P=0.33) and mOS (11 vs. 8 months; P=0.33) with cFTM/BEV. Unmethylated patients experienced the greatest survival benefit with the multimodal approach (mPFS: 10 vs. 5 months; mOS 11 vs 6 months; both P=0.02) and cFTM/BEV (mPFS: 5 vs. 2 months; mOS 6 vs. 3.2 months; both P=0.01). In conclusion, in recurrent MGs, multimodal therapy and cFTM/BEV provide survival and response benefits. Methylated patients benefit from a cFTM/BEV but not from a multimodal approach. Notably, unmethylated patients had the highest survival benefit with the two strategies.

Reoperation for Recurrent Glioblastoma Multiforme

The role of reoperation for glioblastoma multiforme (GBM) recurrence is currently unknown. However, multiple studies have indicated that survival and quality of life are improved with a repeat operation at the time of disease recurrence. Prognosis is likely interdependent on several factors, including age, functional status, initial resection status, disease location, and surgical efficacy. However, there are significant data indicating no survival benefit for reoperation. This comprehensive literature review considering the controversial question of whether to operate for progressive or recurrent GBM seeks to evaluate the current available evidence and report on its conclusions.

Prognostic factors for survival in adult patients with recurrent glioblastoma: a decision-tree-based model

We assessed prognostic factors in relation to OS from progression in recurrent glioblastomas. Retrospective multicentric study enrolling 407 (training set) and 370 (external validation set) adult patients with a recurrent supratentorial glioblastoma treated by surgical resection and standard combined chemoradiotherapy as first-line treatment. Four complementary multivariate prognostic models were evaluated: Cox proportional hazards regression modeling, single-tree recursive partitioning, random survival forest, conditional random forest. Median overall survival from progression was 7.6 months (mean, 10.1; range, 0-86) and 8.0 months (mean, 8.5; range, 0-56) in the training and validation sets, respectively (p = 0.900). Using the Cox model in the training set, independent predictors of poorer overall survival from progression included increasing age at histopathological diagnosis (aHR, 1.47; 95% CI [1.03-2.08]; p = 0.032), RTOG-RPA V-VI classes (aHR, 1.38; 95% CI [1.11-1.73]; p = 0.004), decreasing KPS at progression (aHR, 3.46; 95% CI [2.10-5.72]; p < 0.001), while independent predictors of longer overall survival from progression included surgical resection (aHR, 0.57; 95% CI [0.44-0.73]; p < 0.001) and chemotherapy (aHR, 0.41; 95% CI [0.31-0.55]; p < 0.001). Single-tree recursive partitioning identified KPS at progression, surgical resection at progression, chemotherapy at progression, and RTOG-RPA class at histopathological diagnosis, as main survival predictors in the training set, yielding four risk categories highly predictive of overall survival from progression both in training (p < 0.0001) and validation (p < 0.0001) sets. Both random forest approaches identified KPS at progression as the most important survival predictor. Age, KPS at progression, RTOG-RPA classes, surgical resection at progression and chemotherapy at progression are prognostic for survival in recurrent glioblastomas and should inform the treatment decisions.

Iridium-Knife: Another knife in radiation oncology

PURPOSE

Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 (¹⁹²Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial ¹⁹²Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife.

METHODS AND MATERIALS

Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk.

RESULTS

Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans.

CONCLUSIONS

Both 3D ¹⁹²Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D ¹⁹²Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife.

The role of brachytherapy in the treatment of glioblastoma multiforme

Brachytherapy (BT) for glioblastoma multiforme (GBM) involves the use of radioactive isotopes to deliver ionizing radiation directly into the tumor bed. Its application as a means to prolong survival in GBM patients over the past few decades has come with variable success. The objective of this review is to describe the utility of BT in GBM, and to report the outcomes and adverse events associated with its use in different multimodal treatment approaches. A search of the literature was conducted using the PubMed database. The most recent search was performed in September 2015. Thirty-two series involving 1571 patients were included in our review. The longest median overall survival (MOS) following BT for newly diagnosed GBM reached 28.5 months. Overall, 1-, 2-, and 3-year survival rates were 46-89 %, 20-57 %, and 14-27 %. For recurrent GBM, the longest reported MOS after BT was 15.9 months. One-, 2- and 3-year survival rates for recurrent GBM were 10-66 %, 3-23 %, and 9-15 %. Adverse events were reported in 27 % of patients. Reoperation for radiation necrosis occurred in 4 and 27 % of patients following low- and high-dose rate BT, respectively. BT is a feasible option for extending survival in carefully selected GBM patients. As patient outcomes and overall survival improve with more aggressive radiotherapy, so does the risk of radiation-related complications. The most effective use of BT is likely as a part of multimodal treatment with other novel therapies.

Attitude and practice of brachytherapy in India: a study based on the survey amongst attendees of Annual Meeting of Indian Brachytherapy Society

PURPOSE

We performed a survey amongst attendees of the 4(th) Annual Meeting of Indian Brachytherapy Society to study the patterns of brachytherapy practice and attitude towards brachytherapy use.

MATERIAL AND METHODS

A 19-point questionnaire was designed and e-mailed to the attendees immediately after the conference. Descriptive analysis of the responses were done and satisfaction index was used as a tool for evaluation of the program effectiveness. Binomial test was used to assess the difference between distributions of responses and Mann-Whitney U test was used to assess the correlation between responses. P value (2-tailed) of < 0.05 was taken significant for all statistical analysis.

RESULTS

Of a total of 202 attendees, 90 responded to the survey (response rate: 44.5%). Seventy-two percent belonged to an academic institute while 28% belonged to non-academic institutes. Eighty-six percent were radiation oncologists and 10% were medical physicists. Eighty-nine percent respondents used high-dose-rate, 14% - pulse-dose-rate, and 13% used low-dose-rate brachytherapy facility. Orthogonal X-rays, computed tomography, and magnetic resonance imaging was used for brachytherapy planning by 56%, 69%, and 14%, respectively. Ninety-three percent of them thought that lack of training is a hurdle in practicing brachytherapy and 92% opined that brachytherapy dedicated meetings can change their perception about brachytherapy. Seventy percent respondents admitted to make some changes in their practice patterns after attending this meeting. Ninety-seven percent of them would like to attend future meetings and 98% felt the need to include live workshops, hands on demonstrations, and video presentations in the scientific programme.

CONCLUSIONS

The survey highlights a positive attitude towards increasing brachytherapy use, and may serve as an important guiding tool in designing teaching and training programmes; thus overcoming the hurdles in successful and widespread use of a quality brachytherapy programme at radiotherapy centers.

Second surgery for recurrent glioblastoma: A concise overview of the current literature

Optimal treatment for recurrent glioblastoma continues to evolve. Currently, however, there is no consensus in the literature on the role of reoperation in the management of these patients, as several studies provide evidence for a longer overall survival in selected patients with recurrent glioblastoma who underwent second surgery and other studies report a limited impact of second surgery in the clinical course. In this paper, a review of the current literature was performed to analyze the role of reoperation in patients with recurrent glioblastoma and to report the overall survival from diagnosis, progression-free survival and quality of life. Using PubMed and Ovid Medline databases, we performed a review of the literature of the last seven years, finding a total of 28 studies and 2279 patients who underwent second surgery, that were included in the final analysis. The median overall survival from diagnosis and the median survival from second surgery were 18.5 months and 9.7 months, respectively. Extent of resection at reoperation improves overall survival, even in patients with subtotal resection at initial operation. Preoperative performance status and age are important predictors of a longer survival, reason why younger patients with a good preoperative performance status could benefit from reoperation.