Video Atlas of Neurophysiological Monitoring in Surgery of Infiltrating Brain Tumors (eBook)

3 The Impact of Lesionectomy on the Prognosis of Infiltrating Intracerebral Tumors

3.1 Evidence for Surgical Resection of Malignant Intracerebral Tumors

The role of cytoreductive surgery and complete or even supramarginal surgical resection of infiltrating cerebral tumors is of utmost importance. Therefore, we will briefly review the existing evidence for surgical resection of low- and high-grade gliomas as well as cerebral metastases.

3.2 Low-Grade Gliomas

As low-grade gliomas have the very real potential of malignant transformation to high-grade gliomas, they need to be considered as functional glioblastoma multiformes (GBMs) (Fig. 3.1) and need to be considered as a precancerous condition as they exhibit a highly infiltrative growth pattern with a diffuse infiltration of still functional brain areas.1 Therefore, a biological complete resection is likely not possible. If biological complete resection is not possible, does a radical tumor resection of low-grade gliomas translate into an improved prognosis at all? Prospective, randomized, and controlled trials addressing this question are not yet available. However, several retrospective studies suggest a benefit of a radical surgical resection of low-grade gliomas.2,3,4,5,6,7,8,9,10,11 In a population-based parallel cohort analysis of low-grade gliomas in patients from two different Scandinavian hospitals, overall survival after early surgical resection was significantly improved as compared to a biopsy and a “wait-and-watch” strategy.11,12 In a retrospective analysis of over 1000 French low-grade gliomas patients, surgical resection translated into increased malignant progression-free and overall survival following extensive surgical resection.13,14 A recent Dutch study with 228 adult patients with WHO II supratentorial gliomas identified the residual tumor volume after resection as a strong predictor for the overall survival.15 These results confirm earlier evidence where the postoperative tumor volume was a prognostic factor of both the progression-free and overall survival.16,17 Current guidelines advocate, therefore, extensive surgical resection as first therapeutic option.18,19 However, postoperative neurologic deficits are a negative prognostic factor. Therefore, surgery should prevent new perisurgical deficits and a sustained quality of life of patients has a priority over maximization of surgical resection.19

3.3 High-Grade Gliomas

Compared to low-grade gliomas, malignant gliomas are similarly highly infiltrating but show a worse prognosis. Evidence for cytoreductive surgery for malignant gliomas was demonstrated in retrospective and prospective studies:20 The beneficial effect of a surgical resection as compared to a biopsy alone was demonstrated already in the 1950s and in two later prospective studies.21,22,23 Moreover, the post-hoc analysis of the prospective randomized and controlled 5-amino-laevulinic acid (5-ALA) study with 270 glioblastoma patients comparing conventional with 5-ALA fluorescence-guided resection identified the postoperative tumor volume as prognostic factor for the overall survival.24,25 The later prospective, randomized, and controlled single-center iMRI study with 58 glioblastoma patients analyzed the impact of the use of an intraoperative MRI guidance on extent of resection. As in the 5-ALA study, the more complete tumor resections in the study group translated in a significantly prolonged progression-free survival.24,26 However, the iMRI was neither designed nor powered for a further analysis of a potential effect of extent of surgical resection on overall survival.27 Based on these data, complete surgical resection of malignant gliomas (if feasible) is standard of care and recommended by the current guidelines.26 Again, although complete surgical resection of malignant gliomas should be aimed at, the preservation of the patient’s neurologic integrity is prior to the maximization of surgical resection.19

3.4 Cerebral Metastases

In contrast to low- and high-grade gliomas, cerebral metastases are more sharply delimitated from the adjacent brain tissue. Nevertheless, most metastases have the properties of albeit limited, but still relevant, local brain infiltration.27,28,29,30 Therefore, treatment of cerebral metastases should aim at the resection of this limited infiltration zone and therefore aim at a local cure. Evidence for a surgical resection of one to four cerebral metastases have been established from phase III studies from the 1990s comparing whole-brain radiation therapy (WBRT) alone with surgery combined with WBRT. In particular in the studies by Patchell and by Noordijk and Vecht, a combined surgical and adjuvant treatment was associated with a significantly improved overall survival.31,32,33 In nearly all more recent phase III studies, overall survival was more related to the systemic status of cancer patients than to the cranial situation.34,35,36,37,38 However, the beneficial role of lesionectomy for a single, accessible metastasis is unquestionable. In other words, an adequate treatment of a single cerebral metastasis by surgical resection (or single-fraction radiosurgery/irradiation) is the prerequisite to shift the prognosis of cancer patients from the cranial situation to the systemic status. However, prospective and controlled studies relating the residual tumor after surgery to the rate of local recurrences and finally to the overall survival are lacking. Nevertheless, retrospective studies suggest such an association.39 Furthermore, extension of surgical resection toward a supramarginal resection might additionally result in a better local control as compared to conventional metastectomy.28,40,41,42,43,44,45 In conclusion, at least complete surgical resection of a single cerebral metastasis is together with single-fraction radiosurgery the first therapeutic option and advocated by the actual guidelines.46,47,48

References

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[2]Duffau H, Lopes M, Arthuis F, et al. Contribution of intraoperative electrical stimulations in surgery of low grade gliomas: a comparative study between two series without (1985–96) and with (1996–2003) functional mapping in the same institution. J Neurol Neurosurg Psychiatry. 2005; 76(6):845–851

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[11]Jakola AS, Myrmel KS, Kloster R, et al. Comparison of a strategy favoring early surgical resection vs a strategy favoring watchful waiting in low-grade gliomas. JAMA. 2012; 308 (18):1881–1888

[12]Jakola AS, Unsgård G, Myrmel KS, et al. Low grade gliomas in eloquent locations - implications for surgical strategy, survival and long term quality of life. PLoS One. 2012; 7(12): e51450

[13]Capelle L, Fontaine D, Mandonnet E, et al. French Réseau d’Étude des Gliomes. Spontaneous and therapeutic prognostic factors in adult hemispheric World Health Organization Grade II gliomas: a series of 1097 cases: clinical article. J Neurosurg. 2013; 118(6):1157–1168

[14]Pallud J, Audureau E, Blonski M, et al. Epileptic seizures in diffuse low-grade gliomas in adults. Brain. 2014; 137(Pt 2): 449–462

[15]Wijnenga MMJ, French PJ, Dubbink HJ, et al. The impact of surgery in molecularly defined low-grade glioma: an integrated clinical, radiological, and molecular analysis....