Astrocytoma or Oligodendroglioma? Precise diagnosis of brain tumors. 4
There are many types of brain tumors. One type is oligodendroglioma. Dr. Anton Titov, MD. It is perhaps the more common type of brain tumor. You are applying an advanced molecular analysis in oligodendroglioma. It can affect the treatment plan and risk stratification of patients with oligodendroglioma. Dr. Anton Titov, MD. Please discuss your work in oligodendroglioma research. There are two aspects of oligodendroglioma diagnosis and therapy. Dr. Sebastian Brandner, MD. One is the research and the other aspect is the diagnostics. First, I would like to focus on the diagnostics. I should say the discovery that a certain chromosomal loss in oligodendroglioma was discovered in early 1990s. Dr. Cairncross discovered a co-deletion of two chromosomal arms. One is 1p, short arm of chromosome 1. Another one is a long arm of chromosome 19. They are co-deleted in oligodendrogliomas. So subsequently this research expanded. It found its way into clinical diagnostics. We actually picked it up in the last 10 to 15 years. Dr. Sebastian Brandner, MD. The molecular diagnostics became more important. Because the treatment plans depended more on the knowledge of this one 1p / 19q co-deletion. In 2008 an American consortium discovered this. There’s a mutation in the isocitrate dehydrogenase, IDH. IDH enzyme is mutant in oligodendrogliomas and astrocytomas. A year later this mutation was found also in other type of tumors. Mutation exists in soft tissue tumors and hematological tumors. Shortly after that Dr. Andreas von Deimling in Heidelberg discovered influence of mutation in oligodendroglioma. His team described very carefully how these IDH mutation relates to astrocytomas and oligodendrogliomas. Findings went subsequently through clinical trials and many other clinical trials. The 1p / 19q chromosomal co-deletion always exists together with the IDH mutation. Another group of IDH-mutant brain tumors do not have the 1p / 19q co-deletion. That group is called “astrocytomas”. That’s how we currently understand the pathology and the pathophysiology of those tumors. Dr. Anton Titov, MD. So there is one common mutation that these tumors have. It is the IDH mutation. Then there’s the 1p / 19q chromosomal co-deletion in oligodendrogliomas. It is IDH loss and p53 mutation in astrocytomas. This is essentially leading to a question. How do we diagnose those tumors? Dr. Sebastian Brandner, MD. How does molecular diagnostics contribute to the better, sharper, and more clearly defined diagnosis of those brain tumors? How do we use those biomarkers? We set up 1p/19q molecular test in our department in 2003. We tested about 10 brain tumors per year. In 2004-05 we did 20 – 30 1p/19q diagnostic tests. Then we started optimizing the methodology of brain tumor diagnosis. We’re doing a PCR-based methodology. We are now providing this diagnostic service for many departments in the country. We do it for neuropathology departments. On the other hand, neuropathology society encourages to establish this tests locally. Because it needs to be available locally. It should be available to patients locally. Brain tumor diagnosis is required by pathologists locally. Dr. Anton Titov, MD. Most major neuropathology centers in the UK have their own neuropathology testing of all those brain tumors. But we provide a very large catchment area in total perhaps 10 to 12 million population. Dr. Sebastian Brandner, MD. We serve different hospitals that refer brain tumor materials to us. So we do lots of those oligodendroglioma and astrocytoma tests. We also do these tests in tumors that are expected to be negative. We have to see how they discriminate between astrocytomas and oligodendrogliomas. Oligodendroglioma and astrocytoma are two types of glioma brain tumors. It is important to make exact brain tumor type diagnosis. Leading expert in molecular brain tumor diagnosis explains key mutations in oligodendroglioma and astrocytoma.
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