Malignant Glioma Surgery: Complication Avoidance:

The impact of surgery in high grade gliomas - a literature review

Malignant gliomas are aggressive brain cancers. After many decades of intensive research they represent a major cause of cancer related mortality and morbidity. Management of malignant gliomas is very difficult. None of the current treatments are curative. High grade gliomas are optimally treated with surgery followed by radiotherapy and chemotherapy. The impact of surgery on progression free survival and overall survival was a constant preoccupation and debate for decades among neurosurgeons. Different studies published in the last 25 years have provided evidence that the extent of resection of high grade gliomas can influence time to progression and median survival, although so far there is no class I prospective randomized trial to fully answer this question. Some of the most important studies are reviewed here. The modern neurosurgery relay on some tools that proved to be very helpful in guiding the surgeon to achieve the maximal tumoral cytoreduction with minimum impact on the brain’s eloquent areas. iMRI has been proved to be safe and became an important tool during tumor surgery, used alone or in conjuction with other important techniques: intraoperative neurophysiology, awake cortical mapping, 5-ALA fluorescence etc. Although so far the prognostic of high grade gliomas is still disappointing, further understanding of the biology of these tumors and a patient-tailored treatment could be the keys of finding a cure in the future.

Molecular mechanisms of temozolomide resistance in glioblastoma multiforme

Glioblastoma multiforme (GBM; WHO astrocytoma grade IV) is considered incurable owing to its inherently profound resistance towards current standards of therapy. Considerable effort is being devoted to identifying the molecular basis of temozolomide resistance in GBMs and exploring novel therapeutic regimens that may improve overall survival. Several independent DNA repair mechanisms that normally safeguard genome integrity can facilitate drug resistance and cancer cell survival by removing chemotherapy-induced DNA adducts. Furthermore, subpopulations of cancer stem-like cells have been implicated in the treatment resistance of several malignancies including GBMs. Thus, a growing number of molecular mechanisms contributing to temozolomide resistance are being uncovered in preclinical studies and, consequently, we are being presented with a broad range of potentially novel targets for therapy. A substantial future challenge is to successfully exploit the increasing molecular knowledge contributing to temozolomide resistance in robust clinical trials and to ultimately improve overall survival for GBM patients.

Cytoreductive surgery of glioblastoma as the key to successful adjuvant therapies: new arguments in an old discussion

BACKGROUND

This article discusses data from 3 randomized phase 3 trials, supporting a role for surgery in glioblastoma.

METHODS

Data were reviewed by extent of resection during primary surgery from the ALA-Glioma Study (fluorescence-guided versus conventional resection), the BCNU wafer study (BCNU wafer versus placebo), and the EORTC Study 26981-22981 (radiotherapy versus chemoradiotherapy with temozolomide).

RESULTS

For glioblastoma patients in the ALA study, median survival was 16.7 and 11.8 months for complete versus partial resection, respectively (P < 0.0001). Survival effects were maintained after correction for differences in age and tumor location. For glioblastoma patients who received ≥90% resection in the BCNU wafer study, median survival increased for BCNU wafer versus placebo (14.5 versus 12.4 months, respectively; P = 0.02), but no survival increase was found for <90% resection (11.7 versus 10.6 months, respectively; P = 0.98). In the EORTC study, absolute median gain in survival with chemoradiotherapy versus radiotherapy was greatest for complete resections (+4.1 months; P = 0.0001), compared with partial resections (+1.8 months; P = 0.0001), or biopsies (+1.5 months; P = 0.088), suggesting surgery enhanced adjuvant treatment.

CONCLUSION

Complete resection appears to improve survival and may increase the efficacy of adjunct/adjuvant therapies. If safely achievable, complete resection should be the surgical goal for glioblastoma.

Safety profile of carmustine wafers in malignant glioma: a review of controlled trials and a decade of clinical experience

BACKGROUND

Carmustine (1,3-bis [2-chloroethyl]-1-nitrosourea, or BCNU) wafers are approved for recurrent glioblastoma and newly diagnosed malignant glioma (MG). Based on considerable clinical experience and use in multimodal regimens, the safety of BCNU wafers needs a re-evaluation.

SCOPE

A review of literature from 1996 to February 2008 was conducted on the safety of BCNU wafer in MG patients using search criteria in Medline, EMBASE, and BIOSIS. Abstracts from relevant US and European meetings were also evaluated. Three Phase III (two were pivotal) and 26 non-Phase III studies met inclusion criteria. Overall incidence was estimated for each adverse event (AE), and data from individual studies were summarised as median (range) rates. Comparisons were based on consistent similarities or differences across overall incidence, median rate and range.

FINDINGS

BCNU wafer group AE rates from the two pivotal Phase III trials ranged from 4-23% for cerebral oedema, 4-9% for intracranial hypertension, 14-16% for healing abnormalities, 5% for CSF leaks, 4-5% for intracranial infection, 19-33% for seizures, 10% for deep vein thrombosis, and 8% for pulmonary embolus. There were no notable differences in AE rates between the two pivotal Phase III and 26 non-Phase III studies. For the non-pivotal studies, the overall incidence of AEs was low, ranging from 0.2% for intracranial hypertension to 9.6% for healing abnormalities. Healing abnormalities, intracranial infection, and seizures were the most consistently reported AEs, having been observed in 16, 12, and 11 studies, respectively. Rates of healing abnormalities appeared higher in recurrent than in newly diagnosed disease. There were no notable differences between BCNU wafer plus adjuvant treatment (e.g., temozolomide) and BCNU wafer alone, with the exception of haematologic toxicity.

CONCLUSION

This review of safety data for BCNU wafers provides reassurance that the AE rates reported in current treatment strategies including multimodal treatment approaches are comparable to those observed in the initial registration studies. The broad range of AE rates may reflect differences in the perioperative and postoperative management. Clinical experience suggests that strategies may exist to reduce the risk of complications.

Surgery for high-grade gliomas in a developing country: survival estimation using a simple stratification system

BACKGROUND

In spite of great technological advances in diagnostic and therapeutic tools, survival in patients with HGG has not changed significantly in the last years. Judicious management in each case needs survival estimation after surgery. We used a simple stratification system evaluating the histology, patient's age, and the KPS.

METHODS

We retrospectively made an analysis of survival in 103 patients with HGG operated in a 10-year period (1990--1999). Three significant prognostic variables were studied: histology, patient's age, and KPS. The BS-MG was calculated, adding the partial score (0 or 1) obtained for each variable. This score ranges from 0 (worse condition) to 3 (best condition).

RESULTS

Overall, MS was 12 months. For glioblastoma multiforme, AA, and ODS, it was 10, 20, and 19 months, respectively (P = .0001). Patients 44 years old or younger had an MS of 28 months, higher than 10 months for patients older than 45 years (P < .0001). Median survival was 20 months for patients with KPS 80 or higher, and 9 months for those with KPS 70 or lower (P = .02). It was 3.5 months in patients with BS-MG = 0, 9 months for BS-MG = 1, 22 months for BS-MG = 2, and 55 months for BS-MG = 3 (P < .0001.).

CONCLUSIONS

Survival presented here is comparable with those previously reported despite lacking the most sophisticated surgical technique. The stratification score that includes the 3 most important variables for survival seems to be simple and reliable for survival estimation.