Why is malignant glioma highly aggressive?

Why is malignant glioma highly aggressive?  There is no doubt that the aggressive behavior of malignant glioma in the treatment of brain tumors is still a complicated problem.

The destructive and invasive growth of glioma is still rarely accompanied by the metastasis of other systems.However, in terms of the proteases, active factors, and in vitro characteristics expressed by the tumor, glioma and other tumors with distant metastasis are not obvious. different.

Clinical spread type

adjacent parts spread

The autopsy report showed that 45% of glioblastomas (GBM) grow more than one lobe, 25% invade the entire cerebral hemisphere, and 25%-30% of tumors can invade the contralateral hemisphere. Nearly 60% of the supratentorial hemisphere gliomas spread forward or backward, and nearly 20% of the tumors invaded the deep structures of the supratentorial hemisphere and spread vertically along the nerve fiber bundles to the subtentorial.

Frontal glioma can involve the contralateral side through the hydrazine callosum (CC), while temporal glioma often involves the midbrain and pons. These can occur in both high-grade and low-grade gliomas. And those gliomas that originated below the corpus callosum have limited upward spread, and most of them invade the basal structures along the corticospinal tract, such as the thalamus, cerebral peduncle, etc. Tumors that spread to both sides are found in the thalamus, hypothalamus and anterior thalamus, especially the basal node area.

Scherer found that all thalamus and hypothalamic gliomas spread to both sides. Tumors in the pons usually spread to the cephalic side and invade the midbrain and thalamus, and it is rare to spread to the upper cervical spinal cord caudally. For untreated tumors, new tumor cells can be found within 3cm of the necrotic tissue. In recurrent cases, the spread of tumor cells is far beyond the primary tumor, and 80% of the cases can spread to the contralateral hemisphere.

Relapse far away

Recently, all the treatments for high-grade gliomas have no obvious effect. Since Kramer proposed the application of whole brain radiotherapy for local lesions in 1959, people have conducted extensive research on the recurrence pattern of gliomas.

Tumor recurrence can be in situ or adjacent sites (recurrence in situ), or in a remote site (recurrence at a distance), the latter refers to recurrence in an area more than 2 cm away from the original lesion. Autopsy showed that radiotherapy can partially control the recurrence of local lesions (50% of cases have no recurrence in the original area), but the incidence of distant recurrence will increase, from 3% without radiotherapy to 19%-22%.

Clinical studies have found that 5%-7% of patients with high-grade tumors have lesions outside of the original lesion area at the first visit. From the perspective of the spread of the lesion, the recurrence completely outside the original lesion accounted for 2%-25%, and the recurrence partly beyond the original lesion accounted for 23%~48%.

Multifocal glioma

Multifocal gliomas can be divided into continuous type and discontinuous type according to location, or divided into synchronous type (discovered at the first visit) and asynchronous type (discovered during follow-up) according to time. Gliomas found at the same time but at different locations are called multiple gliomas, and gliomas found at different times and at different locations are called multicentric gliomas.

Surgical treatment, radiotherapy and other adjuvant treatment measures have prolonged life span and delayed recurrence, but also increased the incidence of multifocal glioma. Multifocal gliomas accounted for about 1.5% of the first diagnosed cases, and after treatment, multifocal gliomas accounted for 7.5%. In an autopsy of 209 cases of glioma, multiple glioma accounted for 27.8%, and its ratio to multicentric glioma was 10.6:1. Other research centers may find a higher incidence, but it may be caused by a shift in the frame of reference: In another study of malignant glioma, multifocal glioma accounted for 30% of the 47 cases first diagnosed, and It accounts for 56% of the 25 relapsed cases.

Multiple lesions are the result of tumor cell invasion of monoclonal origin. The longer the invasive growth of glioma cells, the greater the incidence of multifocal glioma. Anaplastic astrocytoma is more invasive than glioblastoma. Therefore, multifocal gliomas are more common in anaplastic astrocytomas. For the first diagnosed case, the incidence of multifocal glioma was 4.3% in low-grade degenerative astrocytoma, which was higher than the 0.98% incidence in glioblastoma. For the treated cases, 18 of the 405 cases (4.4%) had multifocal lesions in glioblastoma, compared with 54 cases (8.56%) of the 630 cases of anaplastic glioma. Sexual disease.

(source:internet, reference only)

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