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Will low-grade gliomas worsen into high-grade gliomas?

Will low-grade gliomas worsen into high-grade gliomas? Will low-grade gliomas get worse?

Low-grade gliomas are primary brain tumors classified by the World Health Organization (WHO) classification system into primary and secondary brain tumors, which mainly occur in children and adolescents. The more common low-grade gliomas include WHO II grade hairy astrocytoma, WHO II grade diffuse astrocytoma (including fibroblasts, astrocytes, and protoplasmic variants), oligodendroglioma, and mixed type. Glioblastoma.

Astrocytoma itself is important because it is easier for patients with malignant progression. The prognosis of patients with low-grade glioma is better than that of patients with high-grade glioma. The median survival time of patients with low-grade glioma is 5 to 10 years, while the median survival time of patients with malignant glioma is only 14 months (GBM). Although this is a more favorable prognosis, patients with low-grade glioma may survive up to 20 years. In 50-75% of patients, low-grade gliomas continue to grow and often progress to higher levels, eventually leading to neurological disability and death. In adults, different prospective studies have reported many prognostic factors, which have been shown to affect the survival rate of patients with low-grade glioma, the most consistent histological type, the age of the patient, and the extent of resection (postoperative magnetic resonance imaging) And tumor size. The 10-year survival rate of pilocytic astrocytoma is about 80% anywhere (cerebral hemisphere, cerebellum or spinal cord), but the survival rate is 100% in patients with brain tumors undergoing total tumor resection. In the diffuse low-grade malignant tumor group, the prognosis is significantly different according to the histological type of the tumor.

Will low-grade gliomas worsen into high-grade gliomas? Factors associated with improved survival in patients with glioma include younger age, higher KPS score, pathology of oligodendroglioma, postoperative radiotherapy, and total tumor resection. Preoperative enhancement, tumor size, and subtotal resection are related factors for tumor recurrence or malignant transformation.

The annual incidence of low-grade glioma is about 4,700, which is about one-third of that of high-grade glioma. This relatively low incidence hinders the development of standardized treatment options. Treatment may include monitoring, biopsy, surgery, radiotherapy, or chemotherapy, and may vary in different centers, locations, and clinical manifestations. Over time, most tumors will recur or undergo malignant transformation. The results differ between different studies. The 5-year progression ranges from 50% to 70%, and the malignant tumor-free survival rate ranges from 30% to 70%.

In our study, only one patient had a PFS (Progressive Free Survival) of 84 months, while the other patients relapsed and progressed rapidly, leading to neurological deterioration and subsequent death. This heterogeneity of patient evolution makes it necessary to determine some factors related to the survival, recurrence, and malignant development of patients undergoing low-grade glioma resection.

Factors related to improving survival rates include:

Age (under 40).

In our series, 3 patients are younger than 40 years old, but their prognosis is not better than that of patients over 40 years old because our series is small and uneven.

Higher KPS score.

Will low-grade gliomas worsen into high-grade gliomas? The pathology of oligodendroglioma, FAs and oligodendroglioma patients also have similar recurrence and/or development. Although FAs tend to develop into larger and higher grade tumors than patients with oligodendroglioma, this may be because FAs are mainly composed of abnormal astrocytes and are more prone to malignant transformation.

After postoperative radiotherapy, although the PFS of patients receiving radiotherapy improved immediately, it did not translate into an improvement in OS. In addition to prolonging the time for tumor progression, radiation therapy has other potential benefits, such as controlling symptoms, especially seizures. In our series, 5 patients received radiotherapy, 2 patients received both radiotherapy and chemotherapy, but PFS and 5 patients were not affected.

Surgical resection results (<1cm residual tumor). Resection range (based on residual disease volume), tumor size and the possibility of tumor recurrence, recurrence time, and grade of tumor recurrence were negatively correlated. Recent studies have shown that independent total resection reduces the risk of malignant transformation, indicating that total tumor resection should follow the principle of complete resection of these tumors. A critical point of total resection is a precise definition. For low-grade gliomas, this means removing T2 from all high signal areas, so only the tumor volume before and after MRI can be compared.

How to improve the survival rate of glioma? High-safety resection is the preferred method.

Will low-grade gliomas worsen into high-grade gliomas? For early gliomas, surgery is undoubtedly still the main treatment option. The principle of surgical treatment is to remove the tumor as much as possible and try to protect the normal tissues. Studies have shown that the degree and scope of tumor resection are closely related to the survival of patients and are independent prognostic factors. However, the invasive growth of glioma has no obvious histological boundary with normal brain tissue, and it is difficult to achieve a true total resection. Therefore, various surgical assistive technologies have emerged. Microneurosurgery is one of them. Because gliomas are invasive growth, it is difficult to accurately distinguish their histological boundaries only by experience and naked eyes.

Advantages of microneurosurgery: In recent years, with the rapid development of microsurgery, laser, ultrasound and neuroendoscopy, microneurosurgery has increasingly shown its advantages. Compared with traditional surgery, microsurgery can more accurately remove tumors, to a large extent accurately and efficiently determine brain functional areas, correct errors caused by brain displacement during surgery, and provide real-time feedback on the scope and extent of tumor removal. Avoid tumor residues and protect the normal tissues around the tumor, thereby maintaining normal brain tissue and nerve function to a large extent after tumor resection, greatly reducing postoperative complications, enabling patients to recover faster and better, and reducing the occurrence of complications rate.

The other group analyzed the prognosis of 492 glioma patients after microsurgery. The 3-year survival rate for patients with grade ⅰ glioma is as high as 87.25%, the 3-year survival rate for patients with grade Ⅱ glioma is 55.09%, and the 3-year survival rate for patients with grade ⅰ-ⅳ glioma is 43.09%. The overall prognosis is obvious, and the survival rate is significantly higher than that of traditional surgery.

How to choose postoperative treatment for glioma?

Will low-grade gliomas worsen into high-grade gliomas? In addition to surgery, radiotherapy is also an important means of treating glioma. It mainly uses the physical effects of various radiations to kill or inhibit the growth of tumor cells. A series of clinical studies have proved that it can improve the cure rate and median survival of glioma patients, and relieve symptoms to a large extent. In addition, drug chemotherapy is a commonly used method, and there are many types of chemotherapy drugs, among which temozolomide (TMZ) and bevacizumab have outstanding curative effects and become first-line drugs. Temozolomide (TMZ) can significantly prolong the survival time of patients with high-grade glioma.

Will low-grade gliomas worsen into high-grade gliomas? Targeted drugs, immunotherapy, clinical trials, etc. : Targeted therapy of glioma mainly refers to drugs that inhibit angiogenesis, such as bevacizumab, which can significantly reduce cerebral edema, improve the quality of life of patients, and prolong the progression-free survival of patients, but they cannot improve the overall survival of patients. Bevacizumab combined with irinotecan can be used to save patients with relapsed glioblastoma. Studies have shown that rituximab can also be used to treat glioma. There are many clinical trials on gliomas, such as CAR-T, DC cells, PD-1, PD-L1, etc.

In recent years, with the development of nanotechnology and medical polymer materials, magnetic particles loaded with chemotherapeutic drugs are used as a new targeted chemotherapy system. Under the action of an external magnetic field, the chemotherapeutic drugs will focus on the target area, increasing The local drug concentration can effectively play its role in killing tumor cells and provide more and better methods for the treatment of glioma.

(source:internet, reference only)

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