Brain tumors: malignant glioma

Since the diagnosis of Ted Kennedy with a malignant glioma, the focus has again turned to brain tumors. Let me discuss in this post a little about malignant gliomas. Glioma are one of the most common primary brain tumors. They are called gliomas because the tumor arises from the glial cells (the tumor does not arise from neuronal cells, rather from glial cells which form the structural supporting cells in the brain).

The WHO (world health organization) grades gliomas into 4 classes:

1) Grade I and II gliomas: are also what are called low grade gliomas. These are slow growing tumors, usually seen in the younger age groups. As they are slow growing, they are less malignant and compatible with a longer survival. They ususally present clinically with a seizure (when they irritate the underlying brain) or when they grow in size and become large, they present with mass effect (the mass and bulk of the tumor presses on surrounding structures and patients may present with weakness on one side). How are low grade gliomas treated?

Treatment of low grade gliomas; as these tumors are slow growing, they are at times amenable to surgical resection. This is because these tumors are usually well encapsulated and its margins are well defined. So in children or adults, if we catch these tumors in time and if the tumor does not involve the eloquent cortex (parts of the brain which subserve speech, or control the hand and leg movements), one may be able to resect the entire tumor out enbloc. In some patients, that is all what may be needed and we usually like to avoid radiation in children ( since radiation has its own problems and may cause cognitive deficits in the young child later on). You doctor may also put you on an anti-seizure medication for a short while to prevent you from having seizures.

Grade III and IV gliomas: or high grade gliomas. This includes glioblastoma multiforme or GBM. Since these tumors are high grade, they are usually fast growing and invade the surrounding brain tissue. Hence it is impossible to resect the entire tumor out usually. Even if you resect the entire tumor you see macroscopically (that is with the naked eyes), the tumor has already caused microscopic metastasis and spread in the brain. Here in lies the fact why these tumors are so hard to treat and patients usually have a poor prognosis. In the best centers in the world, we treat these tumors with a combination of surgery ( try to debulk the tumor and remove some of it and decrease the pressure in the brain), radiation (you may either radiate just the tumor or irradiate the entire brain to prevent metastatic spread) and chemotherapy. Radiation and chemotherapy may either be used concurrently  to supplement each other or one after the other. Again usually these tumor present at first with seizures and your doctor may start you on an anti-epileptic drug to prevent it.

I shall build on this discussion in my next post. Enjoy the weekend everyone, it is a beautiful day here in NYC.

Personal Regards,

Nitin Sethi, MD

Brain tumors primary Vs secondary (what we know and what we don’t)

This is a continuation of my earlier post on brain tumors where I went over the classification of brain tumors, their presentation (what signs and symptoms they present with) and briefly discussed about their management.

Primary brain tumors that is tumors which arise from the brain itself need to be differentiated from secondary brain tumors or metastatic spread of tumor to brain (this refers to a tumor which arise somewhere else as for example in the lung and then spreads to the brain. That is the primary site of the tumor is the lung and then it has metastasis to the brain). Various tumors can spread to the brain but the most common among them are:

1) Lung tumor–most common cause of lung tumor is smoking and it commonly spreads to the brain. Infact many times it is first detected only when it has spread to the brain. that is the time the patient either has a seizure or develops weakness on one side of the bogy. When a CT scan or MRI scan of the brain is done a tumor is found and when further investigations are done like Chest X-ray and CT scan of the chest the primary is found to be the lung. Lung tumor may produce multiple metastatic lesions to the brain (by that I mean there are commonly more than one lesion found when the brain is imaged). How does lung tumor spread to the brain you may ask. Well the most common route of spread is what is called the hematogenous route (meaning that some tumor cells from the lung enter the blood stream and are carried to the brain where they develop into secondary tumors).

2) Breast cancer: also commonly spreads to the brain and can present with multiple metastatic lesions. As you can imagine the prognosis is poor once there is evidence of metastatic disease. Thus oncologists (doctors who treat cancer) like to treat cancers aggressively so that they do not spread further and cause widespread disease).

3) Renal cell carcinoma: renal carcinoma may also spread to the brain.

4) Thyroid cancer

5) Colon cancer

6) Choriocarcinoma: choriocarcinoma is usually fulminant and has the potential for causing hemorrhagic brain lesions (meaning that the metastatic lesions in the brain are prone to bleeding).

7) Melanoma: malignant melanoma is frequently seen in the west. It too has the potential for causing hemorrhagic brain metastatic lesions. Hence it is imperative that you follow closely with your doctor if you are diagnosed with melanoma.

As you can imagine the treatment varies if you have a primary brain tumor versus if you have a secondary brain tumor. Treatment decisions also vary depending upon whether you have a solitary brain tumor versus if you have multiple metastatic lesions in the brain. The treatment also depends upon the site (location) of the tumor in the brain. Let me explain this a little further. If the tumor is in a part of the brain which can be easily accessed surgically, is small in size and does not involve any eloquent area of the brain then it more likely that it can be removed surgically. What do I mean by eloquent area of the brain. By eloquent I mean parts of the brain which perform vital functions. So if the tumor involves the speech center of the brain or lies very close to the area which controls the movement of the hand and leg or involves the area of the brain which controls vision, then you can understand that if the surgeon decides to remove it, more than likely the patient has awake from the surgery and be not able to speak or have weakness on one side of the body or may not be able to see. Thus surgical options are limited when tumors involve the eloquent cortex.

Primary brain tumors like glioblastoma multiforme (GBM) rarely ever metasize outside the brain. By this I mean it has been seen that primary brain tumors ususally remain confined to the brain itself and do not spread outside. That said and done, this is not a hard and fast rule and there are cases documented in which a primary brain tumor has spread outside the brain. Primary brain tumors though may spread via the white matter tracts to other parts of the brain and also spread via the cerebrospinal fluid (CSF). So sometimes one may have what we called a multi-centric primary brain tumor. As there are multiple lesions in the brain, this has to be differentiated from a secondary brain tumor (a tumor from outside that has spread to the brain).

Thus usually whenever someone is diagnosed with a brain tumor, multiple other tests are done apart from a MRI brain to rule out a secondary tumor. These include a CT scan of the chest (rule out lung cancer), CT scan of the abdomen and pelvis as well as a bone scan. These investigations also help in determining the spread of the disease and this information is vital in treatment decision making process.

 Dr Sethi