High-grade astrocytomas are often very heterogeneous in their histology and that there can be areas of low-grade histology immediately adjacent to areas of high-grade histology. Tumors will behave according to whatever the highest-grade histology is. One can imagine that with the small sections that are obtained via, for instance, stereotactic biopsies that one could therefore through sampling error come up with the wrong histologic grade. Thus by being able to just physically remove that mass, patients in fact often get significantly better. They are able to better tolerate radiation therapy, which has often been a problem when patients have large masses secondary to increased cerebral edema that can occur following radiation therapy. And that patients are at least palliated by removal of large masses. It probably increases survival when one looks retrospectively at the data. Again, patients who have had large resections tend to do better than patients who haven’t, but again there has been no randomized trial to prove this.
In surgery, the one thing that is clear in the treatment of high-grade astrocytoma is that radiation therapy remains the optimal and the most prudent therapy for this disease. There has been a series of randomized trials dating back to the 1970s and the 1980s that have clearly shown a significant survival advantage for patients treated with external beam standard fractionated radiation therapy. Canadian cymbalta 20 mg – effective major depressive disorder medication. Nevertheless, the role of surgery still remains somewhat limited in that although radiation therapy can nearly triple the survival of patients with high grade gliomas – in the case of glioblastoma that means going from a median survival of three months without radiation therapy to a median of nine months. So while radiation therapy clearly makes a difference, it is not optimal.
However, if one actually looks at the data from radiation therapy, one can see that there appears to be a significant dose response and dose survival curve to radiation therapy. That as those patients get treated with higher and higher doses of radiation, that one begins to see increased survival. Unfortunately, as one gets the higher doses of radiation therapy one gets into more radiation toxicity with the most worst toxicity being radiation necrosis, which in many ways is as bad as the tumor itself, causing cerebral edema and local tissue destruction which is permanent and can be permanently debilitating. There are a number of different technical ways in which we can deliver high doses of boost radiation following the standard fraction of the external beam radiation. From these techniques you’ve probably heard about that they include the things like different types of modified linear accelerators or proton beam therapy. In that sense the idea is always the same, and the idea is to be able to deliver high-dose, focal radiation to the tumor while avoiding important and eloquent intracerebral structures.
In fact most of the phase II and many of the phase II studies looking at high dose focal radiation boost, whether it is done with brachytherapy or whether it’s done with one of these external beam techniques that I’ve just talked about, have shown us what appear to be significant survival advantages in patients treated with this boost focal technology.
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