Why does glioma recur?

When it comes to the word tumor, we all think it is a very scary word. We think that once we have a tumor, our life will soon come to an end, especially malignant tumors. Glioma is a common type, and it will recur repeatedly. What is the reason?

Glioma is the most common malignant tumor in the brain, accounting for about 40% of intracranial tumors. The World Health Organization divides the pathological types of gliomas into four levels, among which grade I is benign glioma, grade II is low-grade malignant glioma, and grade III-IV is highly malignant glioma. Unfortunately, grade I gliomas are rare, while grade IV gliomas account for 50% of gliomas.

Gliomas of grades II-IV will recur. Many patients find it difficult to understand the recurrence of gliomas. They think that the doctor removed the tumor and said that it was removed very cleanly, so how could it recur? In fact, the degree of thoroughness of glioma resection is relative. Generally speaking, doctors remove the tumor visible to the naked eye during surgery, which is considered clean. However, due to the characteristics of glioma's invasive growth, some tumor cells are mixed with normal brain tissue and look like normal tissue, which will deceive the doctor's eyes. Therefore, doctors sometimes expand the scope of resection and remove part of the seemingly normal peritumoral tissue, but even so, they cannot prevent the recurrence of malignant gliomas. The reason is that the degree of infiltration of malignant glioma cells is beyond the imagination of ordinary people. Since brain tissue is functional and does not allow arbitrary resection, the scope of expansion of resection is ultimately limited. Moreover, even if one hemisphere with a tumor is completely removed, a glioma may still grow in the opposite hemisphere.

Surgeons have limited ability to treat this behavior of gliomas, so they can only resort to radiotherapy and chemotherapy. Practice has shown that radiotherapy and chemotherapy do significantly delay the recurrence of malignant gliomas, but they still cannot cure gliomas. It is generally believed that these measures cannot eradicate residual infiltrating cells.

In short, the reason why malignant glioma recurs is mainly due to its invasive growth characteristics. At present, surgery, radiotherapy and chemotherapy cannot eradicate the residual latent tumor cells. But we believe that in time, humans will have more effective measures.