https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(11)61346-9.pdf

Primary brain tumours in adults

Summary Surgical treatment of low-grade gliomas (LGGs) aims to maximise the amount of tumour tissue resected, while minimising the risk of functional sequelae. In this review I address the issue of how to reconcile these two conflicting goals. First, I review the natural history of LGG—growth, invasion, and anaplastic transformation. Second, I discuss the contribution of new techniques, such as functional mapping, to our understanding of brain reorganisation in response to progressive growth of LGG. Third, I consider the clinical implications of interactions between tumour progression and brain plasticity. In particular, I show how longitudinal studies (preoperative, intraoperative, and postoperative) could allow us to optimise the surgical risk-to-benefit ratios. I will also discuss controversial issues such as defining surgical indications for LGGs, predicting the risk of postoperative deficit, aspects of operative surgical neuro-oncology (eg, preoperative planning and preservation of functional areas and tracts), and postoperative functional recovery.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474-4422(05)70140-X.pdf

Lessons from brain mapping in surgery for low-grade glioma: insights into associations between tumour and brain plasticity

Virtual and real brain tumors: using mathematical modeling to quantify glioma growth and invasion.

Objectives: Despite the growing use of intraoperative functional mapping in supratentorial low grade glioma (LGG) surgery, few studies have compared series of patients operated on without and with direct electrical stimulation (DES) by the same team. The present study compared the rate of LGG surgery performed in eloquent areas, the rate of postoperative sequelae, and the quality of resection during two consecutive periods in the same department—the first without and the second with the use of intraoperative electrophysiology. Methods: Between 1985 and 1996, 100 patients harbouring a supratentorial LGG underwent surgery with no functional mapping (S1). Between 1996 and 2003, 122 patients were operated on in the same department for a supratentorial LGG using intraoperative cortico-subcortical DES (S2). Results: Comparison between the two series showed that 35% of LGGs were operated on in eloquent areas in S1 versus 62% in S2 (p Conclusions: The results of the present study allow, for the first time, quantification of the contribution of intraoperative DES in LGG resection. Indeed, the use of this method leads to the extension of indications of LGG surgery within eloquent areas; to a decrease in the risk of sequelae; and to improvement of the quality of tumour resection, with an impact on survival.

https://jnnp.bmj.com/content/jnnp/76/6/845.full.pdf

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

Context There are no controlled studies on surgical treatment of diffuse low-grade gliomas (LGGs), and management is controversial. Objective To examine survival in population-based parallel cohorts of LGGs from 2 Norwegian university hospitals with different surgical treatment strategies. Design, setting, and patients Both neurosurgical departments are exclusive providers in adjacent geographical regions with regional referral practices. In hospital A diagnostic biopsies followed by a "wait and scan" approach has been favored (biopsy and watchful waiting), while early resections have been advocated in hospital B (early resection). Thus, the treatment strategy in individual patients has been highly dependent on the patient's residential address. Histopathology specimens from all adult patients diagnosed with LGG from 1998 through 2009 underwent a blinded histopathological review to ensure uniform classification and inclusion. Follow-up ended April 11, 2011. There were 153 patients (66 from the center favoring biopsy and watchful waiting and 87 from the center favoring early resection) with diffuse LGGs included. Main outcome measure The prespecified primary end point was overall survival based on regional comparisons without adjusting for administered treatment. Results Initial biopsy alone was carried out in 47 (71%) patients served by the center favoring biopsy and watchful waiting and in 12 (14%) patients served by the center favoring early resection (P Conclusions For patients in Norway with LGG, treatment at a center that favored early surgical resection was associated with better overall survival than treatment at a center that favored biopsy and watchful waiting. This survival benefit remained after adjusting for validated prognostic factors.

https://depts.washington.edu/neurolog/images/journalclub/dec2012/Comparison_strategy_low-grade_gliomas.2012.12.19.pdf

Comparison of a strategy favoring early surgical resection vs a strategy favoring watchful waiting in low-grade gliomas.

Serial magnetic resonance images of 27 patients with untreated World Health Organization grade II oligodendrogliomas or mixed gliomas were reviewed retrospectively to study the kinetics of tumor growth before anaplastic transformation. Analysis of the mean tumor diameters over time showed constant growth. Linear regression, using a mixed model, found an average slope of 4.1mm per year (95% confidence interval, 3.8-4.4mm/year). Untreated low-grade oligodendrogliomas or mixed gliomas grow continuously during their premalignant phase, and their pattern of growth can be predicted within a relatively narrow range. These findings could be of interest to optimize patients management and follow-up.

Marie Laure Tanguy

Papers

Continuous growth of mean tumor diameter in a subset of grade II gliomas.