Sen. Kennedy and Glioma

I don't know if everyone caught this in the news, but Senator Edward Kennedy has been diagnosed with a glioma. Regardless of one's politics, this is a real bum rap, and my deepest sympathy goes out to him and his family (who have already had enough tragedy to deal with).

I thought I would summarize briefly what gliomas are and what is probably going to happen.

Gliomas are the most common primary tumors of the brain. Primary means that they originate from brain cells as opposed to cells from some other portion of the body that migrate to the brain. They are called gliomas because they originate in glial cells which are the supportive cells in the brain as opposed to the neurons. (Primary neuron tumors are very, very rare primarily because neurons don't divide very often, and cancer is a disease of uncontrolled cell division.)

Gliomas are classified according to the type of cell that they originate from and what is called the pathological grade. Pathological grade is a number that is assigned to the tumor by a pathologist depending on how the tumor lookings -- mostly by how different it looks from the cell that it originated from.

The type of glioma afflicting Sen. Kennedy has not been definitively established, but by presentation it is either something called glioblastoma multiforme (GBM) or anaplastic astrocytoma. Both are derived from astrocytes. GBM is actually more common -- which is very unfortunate because they are also very aggressive. Anaplastic astrocytomas are less aggressive, but still very serious. Which one the Senator has will have to be determined by biopsy.

Gliomas typically present in a couple of ways. The first is seizures, and this was the case with Sen. Kennedy. The seizures are caused by the expanding tumor irritating the surrounding tissue. Another way that gliomas present is by what are called focal neurological deficits. A focal neurological deficit is when the patient lacks the ability to perform some specific neurological function like speech or vision from one eye. FCDs are also caused by the expanding tumor pressing on an area of the brain and inactivating it. Headaches are another way that tumors present. Finally, particularly with tumors in the frontal lobes, you can see patients with subtle personality changes. Previously, well-mannered and disciplined people can go on spending sprees or become violent and rude.

There are some genetic disorders that predispose to glioma formation including Neurofibromatosis 1 and 2, Li-Fraumeni syndrome, Turcot syndrome and tuberous sclerosis. However, most gliomas are not the result of a genetic disease; we say that most gliomas are sporadic. There is an increased risk associated with age, and there are about 10,000 diagnosed a year. (Incidentally, the much bally-hooed association between cell phones and brain tumors has never been verified. A cohort study of about 400,000 people in Denmark failed to find an association.)

So what is going to happen now? Sen. Kennedy is not my patient, but I think that we can reasonably assume the following.

First, Sen. Kennedy is probably going to need a biopsy to identify what type of tumor it is. This involves sticking a needle into his brain and aspirating a small amount of tumor tissue. This tissue will be stained and inspected by a pathologist.

Second, gets to the treatment and prognosis part. Sadly, the prognosis for both of these cancers is really bad. The median survival for GBM is .7 years. The median survival for anaplastic astrocytoma is 2.2 years for people with just surgery and about 5 years for people treated with radiation and surgery.

Treatment for gliomas is usually a mixture of chemotherapy, radiation, and where possible surgery. The problem with the surgery is 1) it's in the brain and that's tough to begin with and 2) these tumors are often not well circumscribed. Brachytherapy -- the seeding of radioactive particles into the tumor -- is also used. Particularly with GBM, the problem with all these treatments is that they often do shrink the tumor considerably, but it always comes back. It is better with anaplastic astrocytoma, but with GBM the treatment benefits are measured in weeks or months, not in years. The question for Sen. Kennedy and his family is how much they want to fight. The answer to that question will in part be determined by the final diagnosis, but also relates to the Senator's quality of life and what he would like to do with the end of it. It is not a decision that anyone else can make for them.

Since I know that someone will ask: the ability of the Senator to function with this disease is really variable. It will really depend on whether they shrink the tumor, where the tumor is, time, and a million other factors. In his particular case, the tumor is located in the right left parietal lobe. The right left is where language comprehension is located in most people. (Nearly 100% of right-handed people and about 70% of left-handed people.) A mass pressing on his right parietal lobe could disrupt his ability to understand and speak. It isn't at all certain that will happen, but it is possible.

I think that is all I have on gliomas. Again, I send my heartfelt condolences to Sen. Kennedy and his family. I wish him the best in this very difficult time.

For further reading, the Mayo Clinic site on gliomas is pretty good. For the technically inclined, here are the eMedicine entries for GBM and anaplastic astrocytoma. Also, here is a site that has a variety of pictures of gliomas -- microscopy, gross specimens and imaging.

Below is one of their images. It is a microscope slide of GBM:

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A JAMA The Journal of the American Medical Association study in Feb. 2005 reported that more than 9,000 malignant gliomas are diagnosed annually in the U.S. and that this type of tumor is the second most common cause of cancer-related deaths in people aged 15 to 44. Those with moderately severe tumors typically survive for three to five years, whereas those with severe forms on average live for less than a year. The normal course of treatment for malignant gliomas is a combo of chemotherapy specifically the drug temozolomide (sold as Temodar) and radiation. If operable, though, this treatment course follows surgery to remove the tumor.

http://www.sciam.com/article.cfm?id=ted-kennedy-diagnosed-wit

By interested (not verified) on 22 May 2008 #permalink

Care to comment on this Wired story (and associated research they cite) which claims a link between the glioblastoma multiforme tumor and the herpes virus?


In his particular case, the tumor is located in the right parietal lobe. The right parietal lobe is where language comprehension is located in most people. (Nearly 100% of right-handed people and about 70% of left-handed people.) A mass pressing on his right parietal lobe could disrupt his ability to understand and speak. It isn't at all certain that will happen, but it is possible.

I think you mean left parietal lobe.

By sobriquet-defect (not verified) on 22 May 2008 #permalink

interested,

I don't know that much about Temodar. I know that it is an alkylating agent -- something that adds an alkyl group to DNA and inhibits replication and that they use it to sensitize the tumor to radiation.

Levi,

Several viruses have been suggested as risk factors for brain tumors, but none have been proven. With respect to CMV (which is related to herpes but different), the data is actually mixed. Some reports show lots of positive staining for the virus in tumors, and some don't.

sobriquet-defect,

Thank you for catching that. I fixed it.

Jake, thanks for the detailed information.

Other promising drugs are Avastin and Tarceva. There is also some work that suggests calorically restricted ketogenic (high fat, low sugar) diets inhibits growth.

Also, the median is not the message. I don't understand why the press and medical doctors jump on the median survival rates. It's not the proper statistical message.

http://www.cancerguide.org/median_not_msg.html

My best wishes to Senator Edward Kennedy and his family.