Why is the Cancer That Afflicted McCain So Deadly?

On Aug. 25, more than a year after he was diagnosed with glioblastoma, Sen. John McCain passed away at age 81. Most people with this type of brain cancer survive less than two years because there is no cure.  

Dr. Solmaz Sahebjam, Director of the Clinical Research Unit

“Glioblastoma is considered to be advanced by the time of diagnosis,” explains Dr. Solmaz Sahebjam, a neuro-oncologist at Moffitt Cancer Center and director of the Clinical Research Unit. “At this time, it is not curable, meaning there’s no way to eradicate all cancer cells. The aim is to control the tumor for the longest possible time and try to preserve a patient’s quality of life as it is going to be significantly affected by the tumor over time.”

Unlike other brain tumors that start in the body and spread to the brain, glioblastoma starts in the brain or spinal cord. Primary brain tumors are relatively rare, with fewer than 25,000 Americans diagnosed with them each year. Metastasized tumors, however, are more prevalent and an estimated 400,000 are diagnosed in the United States each year.

Dr. Peter A. Forsyth, Chair, Department of Neuro-Oncology

“There are a number of variables that depend on treatment,” said Dr. Peter Forsyth, chair of the Department of Neuro-Oncology at Moffitt. “It used to be that a diagnosis like Sen. McCain’s would come with three months to live. Today’s treatments are much better and we see survival for as long as 22 months in some cases.”

Diagnosing glioblastoma, the most aggressive type of brain cancer, requires surgery and a biopsy. If a tumor is cancerous, treatment can vary based on the patient. Those diagnosed with glioblastoma typically live 10 to 22 months. So what should you know about this disease?

What is it? Glioblastoma Multiforme (GBM) is the most common type of glioma, a brain cancer that develops in the central nervous system’s glial cells. Most glioblastomas are cancerous, and many contain their own blood vessels, allowing them to grow quickly.

Glioblastoma is a cancer that affects the cells found in the brain and spinal cord called astrocytes. This form of cancer most commonly develops in the frontal or temporal lobes of the brain. 

What are the signs? Chronic, unexplained headaches are especially common, as are neurological complications such as seizures and double vision. Not every headache means cancer. But if a headache is out of the “normal” parameters for a patient or other symptoms such as personality or mood changes present themselves, it may be time to see a doctor.

Other glioblastoma symptoms include:

• Vomiting
• Changes in temperament or personality
• Difficulty speaking or responding to other peoples’ speech
• Difficulty swallowing
• Short-term memory loss
• Fainting
• Loss of appetite
• Muscle weakness in the arms or legs 

How is it treated? Surgery is required for both diagnosis and treatment since a biopsy is necessary. The best possible treatment depends on many factors that are unique to a patient, which is why it is important that patients receive a treatment plan tailored to their individual needs. Pinpointing the precise location of a patient’s tumor is key, and treatment is available through several techniques:

• Awake craniotomies, laser ablation and other procedures designed to remove cancerous lesions and alleviate pressure within the skull without causing neurological damage
• Radiation therapy, including intensity-modulated radiation therapy, proton beam therapy, photodynamic therapy and stereotactic radiosurgery, which destroys cancerous cells with targeted beams of radiation
• Chemotherapy, including oral medications and drugs that are injected directly into the intrathecal space in the spine so as to minimize their effects on healthy tissues
• Biological therapies, immunotherapies, genetic therapies and hormone therapies, as well as clinical trials 

Who is at risk for glioblastoma? It’s hard to say. Researchers don’t know yet what causes them and it’s not clear if there is a genetic link. Right now, the only way to know if you’re at risk of a glioblastoma is to know the signs, including drastic changes in headaches or cognitive functions. 

What does future treatment look like? Early studies indicate that a blood test for glioblastoma could be on the horizon. There are also advances in imaging techniques that could possibly mean that biopsies may no longer be necessary. But for now, tissue is still required to test for glioblastoma, which means patients must undergo a procedure.