On July 19, 2017, U.S. Senator John McCain announced that he had been diagnosed with glioblastoma brain cancer: a malignant and aggressive type of brain cancer, which his doctors discovered during a routine screening (Reuters). You may have heard of this type of cancer before: it claimed the lives of Senator Ted Kennedy and Beau Biden (son of Former Vice President Joe Biden). But if this term is news to you, you probably have a number of questions: what is glioblastoma? How is it different from other brain cancers, and how do you treat it? Here, we’ll cover the basics of the disease, and discuss chemotherapy, radiotherapy, immunotherapy, and other experimental therapies that may be available if you or a loved one is battling this often-lethal form of cancer.
WHAT IS GLIOBLASTOMA BRAIN CANCER?
All brain tumors are not alike. Doctors categorize different types of tumors according to the part of the body (and type of cells) in which they originate. For example, some tumors begin in glial cells – kind of cell within the human nervous system. Doctors refer to this very broad category of tumors as gliomas.
Since there are also several different kinds of glial cells (all of which perform different tasks within the nervous system), doctors may then further classify different tumors according to these sub-types of cells. For example, astrocytes are a sub-type of glial cell; tumors that begin in astrocytes are called astrocytomas.
With a biopsy (that is, by removing a sample of cells to analyze under a microscope), doctors are able to classify different types of astrocytomas into even smaller groups. These groups are determined by what the cells in the tumor look like, and how quickly they spread. “High-grade” or “Grade IV” astrocytomas – the fastest growing group – are called glioblastomas. Your doctor also may refer to glioblastoma as “glioblastoma multiforme” or “GBM.” (American Cancer Society).
So, all glioblastomas are astrocytomas, but not all astrocytomas are glioblastomas. (If this is confusing, think of another example – like breeds of cats. All Bengal cats are cats, but not all cats are Bengals).
Around two-thirds of astrocytomas are glioblastomas. Glioblastomas are the most common type of malignant brain tumors in American adults (American Cancer Society).
HOW DO YOU TREAT GLIOBLASTOMA BRAIN CANCER?
Symptoms of glioblastoma brain cancer may vary depending on the size of the tumor and where it is within the brain. Patients may experience headaches, seizures, memory loss, motor weakness, or loss of other cognitive functions (UpToDate [1])
Unfortunately, the prognosis is often poor for many people with glioblastoma brain cancer. The disease often recurs (comes back) even with aggressive treatment, and the median survival for most patients is around 14.6 months. Around 30% of patients live as long as two years, and (according to one study) around 10% may survive five years or more (American Brain Tumor Association).
Younger patients and children tend to fare better than older patients (as is the case with many cancers), though around half of glioblastoma diagnoses occur in patients who are 65 years and older. A variety of factors make treatment more challenging for older patients: they’re more likely to suffer from pre-existing illnesses than young people, for example (some, like Senator McCain, may already be cancer survivors). They tend to take more medications and may be more susceptible to side-effects, which can limit their options for treatment. “Social and economic vulnerability” (access to affordable healthcare) is often another limiting factor in the quality of care that many patients are able to receive (UpToDate [2]).
Along with a patient’s age and overall health, the size, placement, and genetic makeup of the tumor will influence the approach to treatment. There is no “one way” to treat brain cancer: most glioblastoma patients undergo a combination of treatments after their initial diagnoses, including resection (removal of some or most of the tumor with traditional surgery), chemotherapy, radiation therapy, and pharmaceutical therapies (typically temozolomide or bevacizumab) (UpToDate [2]).
RADIOTHERAPY AND RADIOSURGERY
While radiation therapy does not necessarily provide a replacement for first-line treatment with traditional surgery, it’s often accepted as the “single most effective” adjuvent (or, concurrent) therapy for this type of cancer (Cureus).
Radiation therapy is not the same as chemotherapy. In chemotherapy, the patient takes a medication that targets cancerous cells; this medication may be administered orally, intravenously (though an IV), by injection, or topically (on the skin). In radiation therapy – sometimes called “radiotherapy” – radioactive particles like X-rays or protons are aimed at (or placed near) malignant cells for the purpose of killing them. By directing the radiation precisely to the affected area, doctors hope to target cancerous cells while minimizing damage to healthy ones. This kind of precision cancer therapy is especially valuable when treating sensitive areas of the body, such as the brain and spinal cord. Both chemotherapy and radiotherapy may be used to treat glioblastoma.
A type of radiotherapy called “stereotactic radiosurgery” (or “SRS”) is often used to treat patients with recurrent or advanced glioblastoma. Some types of SRS employ a particle accelerator. Others employ a smaller robotic device which fires a thin beam of particles at the affected area (you may have also heard this technology referred to as the “gamma knife” or “cyber knife”). Unlike traditional surgery, radiosurgery is non-invasive (it doesn’t involve an incision) and is painless (NIH/MedlinePlus Medical Encyclopecia).
More clinical trials are required in order to understand exactly how radiotherapy and radiosurgery may best benefit patients with glioblastoma brain cancer. Some doctors champion the approach as our best known option for prolonging survival; others argue that radiotherapy alone is simply not enough to defeat the invasive (and intricate) nature of glioblastoma, and advocate the pursuit of new experimental therapies to combat the disease (UpToDate [3]).
IMMUNOTHERAPY AND OTHER EXPERIMENTAL TREATMENTS
If you’re wondering if experimental therapies are available for glioblastoma, the answer is yes. In fact, clinical trials often present the best treatment option for patients with very aggressive and recurrent glioblastomas (UpToDate [3]).
Because glioblastoma brain cancer is so deadly – and because so many cases recur and progress after initial treatment – the need to develop personalized strategies and new, innovative therapies is immense (UpToDate [3]). Researchers are currently exploring a number of treatments including immune checkpoint inhibitors, genetically-engineered cellular therapies (like CART-T cell therapy, which utilizes a patient’s own modified immune cells to fight the disease), even vaccine-like viruses that attack malignant cells (Washington Post).
Many of these experimental therapies do not provide a replacement for surgical resection and radiation therapy, but doctors are hopeful that these new treatments will offer a greater range of options in creating a personalized, multi-faceted treatment plan for every patient and bolster progression-free survival in more cases.
Navigating the healthcare system is a frustrating and cumbersome task for many patients. Finding a clinical trial can be overwhelming, and it can be difficult to gain access or even learn about your options without the appropriate referral. If you or a loved one are struggling to find the right doctor or treatment, a referral service (like OncoLogic advisers) can help.
IN CONCLUSION
We still have much to learn about glioblastoma brain cancer and how to treat it, but doctors haven’t given up hope. Researchers continue to dedicate their lives and careers to the discovery of new and innovative ways to treat this devastating and deadly disease. If you or a loved one is battling glioblastoma, remember: the fight is always on.
REFERENCES
Reuters – “U.S. Senator John McCain diagnosed with aggressive brain cancer.” Patricia Zengerle, July 19, 2017.
http://www.reuters.com/article/uk-usa-johnmccain-mayo-idUKKBN1A501J
American Cancer Society – “Types of Brain and Spinal Cord Tumors in Adults.” Last Revised: January 21, 2016.
https://www.cancer.org/cancer/brain-spinal-cord-tumors-adults/about/types-of-brain-tumors.html
UpToDate [1] – “Clinical manifestations and initial surgical approach to patients with high-grade gliomas.” Tracy Batchelor, MD, MPH, William T Curry, JR, MD.
American Brain Tumor Association – “Glioblastoma (GBM).”
http://www.abta.org/brain-tumor-information/types-of-tumors/glioblastoma.html
UpToDate [2] – “Management of glioblastoma in older adults.” Tracy Batchelor, MD, MPH and Helen A Shih, MD. Topic Last Updated: May 10, 2017.
Cureus – Stereotactic Radiosurgery for Glioblastoma. Kristin J. Redmond and Minesh Mehta. Published Online: December 17, 2015.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4725736/
NIH/MedlinePlus Medical Encyclopedia – “Stereotactic radiosurgery – CyberKnife.” Yi-Bin Chen, MD; Internal Review and update by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team. Editorial Update: March 3, 2017.
https://medlineplus.gov/ency/article/007274.htm
UpToDate [3] – “Management of recurrent high-grade gliomas.” Tracy Batchelor, MD, MPH, Helen A Shih, MD, Bob S Carter, MD, PhD. Topic Last Updated: May 26, 2017
https://www.uptodate.com/contents/management-of-recurrent-high-grade-gliomas?source=see_link
The Washington Post – “These experimental treatments target brain cancer like John McCain’s.” Laurie McGinley, July 26, 2017
https://www.washingtonpost.com/news/to-your-health/wp/2017/07/26/these-experimental-treatments-target-brain-cancer-like-john-mccains/?utm_term=.cb00d8c0afb8
