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BACKGROUND: Low-grade glioma (LGG) is a slow-growing tumour often found in young adults. Most present with epilepsy, but others can have minimal or no symptoms. LGG is a heterogenous term applied to WHO Grade 1 tumours and WHO Grade 2 gliomas (G2G). As opposed to true ‘low-grade’ lesions like dysembryoplastic neuroepithelial tumours (DNET), G2G are associated with continuous growth and malignant transformation. METHOD: Prospective database analysis of patients treated for LGG at Leeds General Infirmary from 2010–2015 (5.5 years). Inclusion criteria: patients where pathological analysis of excised tumour showed small isolated foci of high-grade transformation within a background of G2G. RESULTS: Since 2010, 130 LGG resections were undertaken in Leeds (77 awake, 53 asleep). Six patients were identified with foci of transformation within a background G2G. These patients were offered a choice between the conventional strategy of upfront adjuvant therapy or an alternative strategy of close monitoring with serial MRI scans. Three patients have had repeat surgery (two to complete the resection, one for tumour growth after 3-years). To date, none have exhibited further high-grade change within the residual tumour or surrounding area. CONCLUSION: We describe a small subset of patients with LGG that have foci of high-grade glioma but exhibited behaviour and growth tendencies similar to G2G. So far, surgical excision alone has been sufficient to control tumour growth without adjuvant therapy. This finding supports the use of early aggressive surgical treatment of G2G. It also throws into question the optimal timing of adjuvant therapy after resection of these tumours. This also confirms that these tumours are pre-malignant and should be made distinct in classification and name from true low-grade (Grade 1) tumours. Therefore we suggest changing the nomenclature of G2G from LGG to Pre-Malignant Glioma whilst reserving the term LGG for Grade 1 lesions.