PURPOSE OF REVIEW: The management of low-grade (grade II) oligodendrogliomas is still controversial, due to their rarity and long-term survival. According to recent WHO 2016 Classification of central nervous system tumors oligodendrogliomas are defined by the coexistence of molecular alterations, such as isocitrate dehydrogenase (IDH)1/2 mutations and 1p/19q codeletion. These tumors have better outcome and higher response to chemotherapy compared with diffuse astrocytomas. RECENT FINDINGS: The association of radiotherapy and procarbazine, lomustine (CCNU), vincristine chemotherapy in low-grade oligodendrogliomas is definitely superior over radiotherapy alone, and yields median progression-free survival and overall survival values exceeding by far 10 years. Chemotherapy alone yields results that are inferior compared with radiotherapy + procarbazine, CCNU, vincristine but may better preserve cognitive functions from radiotherapy-induced damage. Chemosensitivity of oligodendrogliomas is related to a high percentage of O6-methylguanine-DNA methyltransferase methylation and low expression of DNA repair genes. Recurrent defects in mismatch repair pathways may induce hypermutation and secondary resistance to temozolomide, but not to nitrosoureas. SUMMARY: Reoperation at progression following initial chemotherapy is increasingly adopted, thus allowing a further delay of radiotherapy. In the future targeting IDH1/2 mutations following incomplete surgery may represent a new innovative option.
Is chemotherapy alone an option as initial treatment for low-grade oligodendrogliomas?
Ruda R.;Soffietti R.Last
2020-01-01
Abstract
PURPOSE OF REVIEW: The management of low-grade (grade II) oligodendrogliomas is still controversial, due to their rarity and long-term survival. According to recent WHO 2016 Classification of central nervous system tumors oligodendrogliomas are defined by the coexistence of molecular alterations, such as isocitrate dehydrogenase (IDH)1/2 mutations and 1p/19q codeletion. These tumors have better outcome and higher response to chemotherapy compared with diffuse astrocytomas. RECENT FINDINGS: The association of radiotherapy and procarbazine, lomustine (CCNU), vincristine chemotherapy in low-grade oligodendrogliomas is definitely superior over radiotherapy alone, and yields median progression-free survival and overall survival values exceeding by far 10 years. Chemotherapy alone yields results that are inferior compared with radiotherapy + procarbazine, CCNU, vincristine but may better preserve cognitive functions from radiotherapy-induced damage. Chemosensitivity of oligodendrogliomas is related to a high percentage of O6-methylguanine-DNA methyltransferase methylation and low expression of DNA repair genes. Recurrent defects in mismatch repair pathways may induce hypermutation and secondary resistance to temozolomide, but not to nitrosoureas. SUMMARY: Reoperation at progression following initial chemotherapy is increasingly adopted, thus allowing a further delay of radiotherapy. In the future targeting IDH1/2 mutations following incomplete surgery may represent a new innovative option.
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