Previously, brain tumors were diagnosed relatively crudely. Dr. Anton Titov, MD. Basic staining is still the first step in the pathology analysis of brain cancer. But now there is more molecular diagnostics and molecular analysis of brain tumor mutations. This becomes very important for treatment of tumors. It is important for the brain tumor prognosis. Dr. Anton Titov, MD. What is the importance of molecular diagnostics for brain tumor diagnosis and therapy? Dr. Sebastian Brandner, MD. First of all, you are absolutely correct that the mainstay of pathology diagnostics is still the first histology slide. It is a slide that looks like this. It has pink staining. I just give an example. This is the size of a slide - 1 by 3 inches. Sometimes you can see against the background of these little pink flics in the center. These are the brain tumor tissue specimen. So we put this slide first under the microscope. That is the first decision in brain tumor diagnosis. Dr. Anton Titov, MD. What to do next? First of all, there might be a number of tumors, like the benign meningioma, the benign Sometimes a brain tumor arises from the coverings of the brain rather than from within the brain. Meningiomas are usually diagnosed just on this section slide. So it's a fast and cheap brain tumor diagnosis. It gives the best information. Because there is no need to do any further molecular testing. Because there are other factors determining whether this brain tumor will have bad prognosis or a good prognosis. For example, where the brain tumor grows. Sometimes it grows in difficult to reach areas. Bottom of the brain, which is called "skull base”. Then this determines the clinical prognosis. Dr. Sebastian Brandner, MD. The brain tumor that is easily accessible on the surface of the brain can be taken out. Usually these brain tumors don't recur. If meningiomas recur, they are often can be resected a second time. So these are the meningiomas. You can diagnose them just on single H&E slide. Gliomas generally can also be diagnosed on a single H&E simple staining slide, particularly glioblastomas. But there are patients who are younger. Some patients have gliomas that have mutations that I mentioned earlier. Gliomas have IDH mutation. These IDH mutations can be detected with an antibody. This antibody was generated in the laboratory in Heidelberg at the German Cancer Research Center. This antibody detects the glioma mutation. So it's a cheap and quick, pathologist-friendly way to diagnose mutations in a brain tumor. Dr. Sebastian Brandner, MD. The nice thing is that this antibody detects 90% of all IDH mutations. 95% of IDH1 mutations and very rare, so-called IDH2 mutations in glioma. This antibody is then combined with another antibody. That antibody detects a nuclear protein. it should normally be present in the cell in the nucleus. But in some type of brain tumors this protein is lost in the nucleus. These brain tumors are astrocytomas. So the small black dot is lost from the cell’s nucleus. We would normally find this black dot in the middle of the cell, in the nucleus. That loss is characteristic and nearly diagnostic for astrocytoma. Dr. Anton Titov, MD. IDH mutation is present also in astrocytoma brain tumor. Brain tumor diagnosis expert explains precise molecular diagnosis of brain tumor type. Benign meningioma. More aggressive astrocytoma and glioblastoma multiforme (GBM).