We join the millions of Americans in expressing support for Arizona Sen. John McCain and his family following the news of his brain cancer diagnosis. The well-known senator’s case is raising questions and concerns about the prevalence of this type of cancer, its risk factors, and treatment options here in Dallas-Fort Worth.
McCain’s cancer, glioblastoma, is the most common and most malignant form of brain cancer, making up about 15 percent of primary brain tumors. These tumors are formed from the glial precursor cells that provide structural support for neurons–the thinking cells in the brain. The tumors are usually highly malignant because the cells reproduce quickly since they are nourished by a large network of blood vessels, providing ample blood supply for continued rapid growth. Glioblastomas are generally found in the cerebral hemispheres of the brain, but can be found anywhere in the brain or spinal cord.
There are two types of glioblastomas, including primary–also referred to as de novo, and secondary. Primary glioblastoma tumors, the most common and the most aggressive, tend to form and make their presence known quickly and are more commonly diagnosed in patients older than 50. Secondary glioblastoma tumors have a longer, somewhat slower growth history, but are still aggressive. Secondary GBMs evolve from lower grade tumors (grade II and III) and are typically found in people 45 and younger. They represent about 10 percent of glioblastomas.
Glioblastomas can cause various symptoms based on the tumor’s location. People are presented with headaches, nausea, vomiting, and fatigue, but can also experience confusion, change in vision, difficulty with balance, weakness, or seizures.
To put the prevalence of brain cancer in the United States into perspective, an estimated 23,800 new diagnoses of brain and spinal cord cancer (and 12,000 glioblastomas) are expected to be diagnosed this year, compared to approximately 250,000 for breast cancer. Glioblastomas are more common with increasing age, and more common in men than women. In broad terms, the causes of GBMs are mutations in the DNA of the tumor cells, changes in the systems controlling the DNA, and a failure of the immune system to recognize and destroy the tumor cells once they develop, and promising advancements focusing on all these abnormalities are giving patients greater hope.
Traditional Treatment Options
Because the brain is a uniquely sensitive and vital organ, one of the most important considerations in treatment for glioblastoma is precision—and with a special concern for near and long term side effects. Glioblastoma can be difficult to treat because the tumors contain so many different types of cells. Some cells may respond well to certain therapies, while others may not be affected at all. This is why the treatment plan for glioblastoma may combine several approaches. Treatment is based on the type, location, and stage of the cancer, and the patient’s overall health. Treatment methods include surgery, radiation, radiosurgery, chemotherapy, targeted therapy, and Tumor-Treating Fields.
Surgery is often the first treatment, followed by radiation therapy. For some patients who cannot safely have surgery initially—for example, tumors deep in the brain and in sensitive areas–radiation therapy can be given as initial treatment. A pill form of chemotherapy, temozolomide, is routinely given during radiation therapy and up to one year following radiation. TTFs can further slow tumor growth after radiation is completed.
Advanced, More Targeted Therapy
Advanced radiation such as proton therapy is especially beneficial in some brain cancer cases because of its extraordinary precision and ability to spare normal brain tissue. Proton beam therapy uses high energy particles (i.e., protons) to destroy cancer with extreme accuracy. Proton radiation can be delivered directly to tumors, with minimal exposure to surrounding healthy tissue. Due to the unique characteristics of proton therapy, patients may be able to receive higher radiation doses more safely than conventional X-ray therapy. Sparing healthy brain tissue may reduce side effects and improve quality of life during and after treatment. Proton therapy is locally available to North Texans at Texas Center for Proton Therapy in Irving.
Many brain cancer tumors are treated with a multi-modality approach that combines surgery, radiation therapy, and chemotherapy, and experimental therapies in order to optimize patient outcomes.
With all of this information in mind, it is important to remember cancer prevention and screening tests are valuable tools in identifying risk factors for developing cancer. While regular screenings for brain cancer are not recommended, early detection is key, and we strongly encourage you to discuss with your doctor any noticeable symptoms.
Dr. Victor S. Mangona is a radiation oncologist at the Texas Center for Proton Therapy. Mangona completed his specialized training in central nervous system and pediatric tumors at the University of Texas MD Anderson Cancer Center.