The role of chemotherapy
The role of chemotherapy as part of the initial treatment for high-grade gliomas remains somewhat of a question and problematic. This is true even though there have been more than 20 randomized trials, because if one looks at those randomized trials the data on whether chemotherapy is really effective, as far as adding something to the radiation, remains very conflicted. The brain tumor cooperative group itself has conducted three multi-center trials and their data is somewhat conflicted, even though they’ve recommended the use of chemotherapy. Why so much controversy and why are the data all over the place? One of the major reasons simply has to do with the power of randomized trials. It takes nearly 250 patients in each arm of a randomized trial in order to have a 80% probability of detecting a 20% increase in median survival. Most single institutional brain tumor trials enrolled less than 30 patients per arm, and even the large multi-institutional brain tumor trials have enrolled less than 50 patients per arm. And that most trials have not been designed to have the power to pick up potential beneficial effects from some type of therapy like chemotherapy.
Meta-analysis is a statistical method that allows one to combine the results from multiple randomized trials in order to pick up small but potentially important clinically significant outcome differences from different therapies. The database that we used were all randomized trials, published in English between 1975 and 1990. The survivals were determined by Kaplan-Meier survival curves and the standard error of survival was determined by Greenwood’s formula.
For patients who were treated with radiation and chemotherapy, there is a higher statistically significant survival advantage compared to those that were treated with radiation alone. When we looked at the two major histology’s usually found within these randomized trials, that being glioblastoma as well as anaplastic astrocytoma, there appeared to be a survival advantage for both sets of patients.
Although a significantly greater survival advantage for anaplastic astrocytomas. So from this meta-analysis what we have concluded is that chemotherapy followed by external beam radiation is advantageous in adults with malignant glioma, although the survival advantage with anaplastic astrocytomas appears to be significantly greater than those with glioblastoma.
It appears that the relatively late survival advantage that we see in patients with glioblastoma – that meaning that if you actually look at those curves we do not begin to see a survival advantage in patients with glioblastoma treated with chemotherapy – to approximately 12-16 months. Discount levitra professional at online Canada pharmacy. a A funny finding when you consider that most patients with glioblastomas die well before that time, suggests to us that treatment with chemotherapy in patients with glioblastoma preferentially benefits patients with more favorable prognostic factors. What are those prognostic factors in glioblastoma? It’s clear that patients who are younger, who have good performance status and who have minimal postoperative residual tumor are the patients who are destined to do better. Thus, if we are going to treat patients with chemotherapy for blastomas this is the group of patients that we would recommend. Where in fact increasingly so, I’ve become less and less enthusiastic about offering standard post-radiation chemotherapy to patients with glioblastoma anyway.