(2012 condensed version) Chinese Medical Association Neurosurgery Branch Tumor Specialty Group
I. Preface
”The expert consensus on the diagnosis and treatment of malignant glioma of the central nervous system in China has been well received since it was published in October 2009. In order to meet the needs of clinicians and patients, the following contents were added to the consensus in September 2011, in addition to updating the consensus: hairy cell astrocytic glioma, dysplastic neuroepithelioma (DNET), ganglioglioma, ganglioglioma, WHO grade II glioma (e.g. diffuse astrocytic glioma, oligodendroglioma). glioma, oligodendroglioma, and ventricular meningioma), gliomatosis in WHO grade III and IV, medulloblastoma, and supratentorial neuroectodermal tumors. The authors also included neuropathologists, neuroimaging specialists, and rehabilitation specialists. The writing process remained the same as the “consensus” process, in which multiple people consult on an issue, assess the quality of evidence in the literature, and reach a recommendation level according to the five levels of evidence-based medicine, the Common Criteria for Reporting Randomized Controlled Trials (CONSORT), and the Clinical Guideline Evaluation System (AGREE) process. After repeated discussions and modifications, the writing group developed the Chinese Guidelines for the Diagnosis and Treatment of Gliomas of the Central Nervous System for reference and application by clinicians and relevant authorities.
II. Overview
Glioma is the most common primary intracranial tumor, and there are four main pathological types: astrocytoma, oligodendroglioma, ventricular meningioma and mixed glioma. Low-grade gliomas (LGG, WHO grade I-II) include hairy cell astrocytoma, pleomorphic yellow astrocytoma and ventricular canal giant cell astrocytoma. They also include mixed glial neuronal tumors, such as ganglioglioma and embryonic dysplastic neuroepithelial tumors. In the past 30 years, the incidence of primary malignant brain tumors has been increasing year by year. According to the U.S. Brain Tumor Registry, malignant gliomas account for about 70% of primary malignant brain tumors. Among the malignant gliomas, mesenchymal astrocytoma (AA, WHO grade III) and glioblastoma multiforme (GBM, WHO grade IV) are the most common, with GBM accounting for approximately 50% of all gliomas.
The exact pathogenesis of gliomas is unknown; the two risk factors identified so far are exposure to high doses of ionizing radiation and genetic mutations in genes with high epistasis associated with rare syndromes. In recent years, the study of TP53 gene mutations, P53 protein expression and tumor stem cells has been a hot topic in the study of the pathogenesis of malignant glioma.
At present, the diagnosis of glioma mainly relies on CT and MRI. some new MRI, such as DTI, DWI, PWI, MRS, fMRI help to improve the diagnosis and judge the prognosis. PET, SPECT help to identify tumor recurrence and radiation necrosis. And finally, the pathological diagnosis needs to be clarified by tumor resection or biopsy. Morphological observation is still the basis of pathological diagnosis. Some molecular biological markers are important for determining molecular subtypes, individualized treatment and clinical prognosis, such as glial fibrillary acidic protein (GFAP), isocitrate dehydrogenase 1 (IDH1) gene, Ki-67 antigen, etc. (Level I evidence).
Treatment of glioma is based on surgical resection combined with radiotherapy and chemotherapy, etc. The use of functional MRI, intraoperative MRI, neuronavigation, cortical electrical stimulation, and intraoperative arousal anesthesia helps to safely and maximally resect the tumor. Radiotherapy can kill or inhibit residual tumor cells and prolong survival; segmented external radiation therapy has become the standard treatment for malignant glioma. In recent years, multiple dose fractionation methods, multiple radiotherapy modalities [three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), intra-stromal brachytherapy and stereotactic surgery] and the application of new radiotherapy equipment have improved the effectiveness of radiotherapy. Simultaneous radiotherapy with temozolomide (TMZ) combined with adjuvant chemotherapy has become the standard of care for newly diagnosed GBM. How to predict the responsiveness of malignant gliomas to chemotherapeutic agents and reduce chemoresistance is the therapeutic focus of chemotherapy. Endogenous O6-methylguanine-DNA methyltransferase (MGMT) methylation levels and chromosome 1p/19q heterozygosity deletion can be used as predictors of chemotherapy response and prognosis in GBM and oligodendroglioma, respectively.
Nowadays, neuroimaging and treatment of glioma have made some progress, but the prognosis of glioma is still not significantly improved. The treatment of glioma requires multidisciplinary cooperation among neurosurgery, radiation therapy, neuro-oncology, pathology and neuro-rehabilitation, with individualized and comprehensive treatment, following evidence-based medical evidence (based on Class I evidence as much as possible), optimizing and standardizing treatment protocols with the aim of achieving maximum therapeutic benefit, extending patients’ progression-free survival and improving the quality of survival as much as possible.
The imaging diagnosis of glioma is strongly recommended to be based on MRI scan plus enhancement, supplemented by CT. MRI scan plus enhancement can not only distinguish glioma from some non-tumor lesions and avoid unnecessary surgery, but also help to grade glioma, detect intraoperative displacement of tumor in real time, clarify the scope of glioma invasion, help to select the area for stereotactic biopsy of tumor, and facilitate the resection of glioma and prognostic assessment. MRI special functional examinations, PET and SPECT are recommended for differential diagnosis, preoperative assessment, efficacy evaluation and postoperative follow-up. The results of MRI plain and enhanced scans of different gliomas are shown in Table 1.
Table 1: MRI scan and enhanced scan results of different gliomas.
Glioma type MRI plain scan MRI enhancement Hairy cell astrocytoma tumor solid part showed slightly low signal in T1WI and slightly high signal in T2WI; cystic part showed low signal in T1WI and high signal in T2WI and water suppressed T2WI.
The solid part of the tumor showed obvious heterogeneous enhancement; the cystic part showed no enhancement or delayed enhancement.
Hairy cell mucinous astrocytoma is usually well-defined, and cystic lesions are rare, showing slightly low signal or equal signal in T1WI and high signal in T2WI.
There is obvious uniform enhancement.
The solid part of pleomorphic yellow astrocytoma shows slightly low signal in T1WI and slightly high signal in T2WI; the cystic part shows low signal in T1WI and high signal in T2WI, and water suppression shows low signal in T2WI.
The solid part and wall nodules are obviously enhanced; the cystic part is not enhanced, and the adjacent meninges of the tumor are often involved and obviously enhanced.
Astrocytoma WHO grade II tumor is a homogeneous mass with poorly defined borders and sometimes even diffuse infiltrative distribution of abnormal signal without a specific mass, or both a mass and diffuse abnormal signal; T1WI slightly low signal or equal signal, T2WI slightly high signal; cystic lesions have T1WI low signal and T2WI high signal.
There is usually no enhancement or only slight inhomogeneous enhancement.
Oligodendroglioma WHO grade II tumors are often heterogeneous, with solid tumors showing slightly low signal on T1WI and slightly high signal on T2WI, and calcifications showing significant inhomogeneous low signal on gradient-echo T2WI.
About 50% of the tumors showed heterogeneous enhancement.
The signal of ventricular meningioma tumor is not homogeneous, with equal or slightly low signal in T1WI and slightly high signal in T2WI, while the cystic lesion shows low signal in T1WI and high signal in T2WI, and the calcification shows significant inhomogeneous low signal in gradient echo T2WI.
Moderate heterogeneous enhancement was observed.
Vascular-centered glioma is well-defined and shows slightly low signal in T1WI and slightly high signal in T2WI, and tumor extension to the adjacent lateral ventricle is seen.
There is no enhancement.
Embryonal dysplasia type neuroepithelioma tumor shows slightly low signal in T1WI and slightly high signal in T2WI, and the “vesicle sign” is often seen in the tumor.
There is usually no enhancement or slight enhancement.
Cystic solid ganglioglioma shows solid wall nodules within cystic lesions, with cystic components showing low signal T1WI and high signal T2WI.
It may show different degrees of enhancement.
The solid part of central neuroblastoma shows equal signal in T1WI and slightly high signal in T2WI, the cystic lesion shows low signal in T1WI and high signal in T2WI, the calcification shows low signal in T2WI, and the gradient echo sequence shows significant low signal in T2WI with moderate to significant enhancement.
High-grade gliomas are usually mixed-signal lesions with iso- or low-signal T1WI and heterogeneous high-signal T2WI, and tumors often spread along white matter fiber bundles.
The tumor often spreads along the white matter fiber bundles. It shows nodular or irregular ring-like enhancement. Tumor angiogenesis is obvious. Gliomatosis is mostly non-enhancing or slightly plaque-like enhancement.
Medulloblastoma is more homogeneous low signal in T1WI, iso- or slightly high signal in T2WI, with clear margins, and may have a small portion of cystic changes.
Most of the tumors are clearly and uniformly intensified, and a few are moderately intensified.
PNET shows slightly low signal in T1WI and slightly high signal in T2WI, or mixed signal intensity in both T1WI and T2WI. Tumor diffusion along the cerebrospinal fluid can be seen.
Heterogeneous intensification, irregular “ringing” intensification, and occasional diffusion along the ventricular canal are seen.