Ahead of World Brain Tumor Day, an expert from global health system Cleveland Clinic is urging individuals not to ignore prolonged or unexplained neurological symptoms as these could be caused by a benign or, much more rarely, cancerous brain tumor, in which case early diagnosis and treatment could significantly improve outcomes.
“The vast majority of brain tumors are benign, but the symptoms of benign and cancerous tumors can be exactly the same,” says neuro-oncologist Mark Malkin MD. “This is because the symptoms are caused by the pressure exerted on the brain by the tumor, as well as the tumor’s location, and the part of the body controlled by that portion of the brain.”
Symptoms caused by pressure can include changes in thinking, mood, balance, vision, spontaneous vomiting or sudden headaches, says Dr. Malkin. Location-related symptoms occur, for example, when a tumor in the frontal lobe causes difficulties in the areas it controls such as focus, concentration and multitasking. Similarly, a tumor in the cerebellum might lead to difficulties in balance, dexterity or coordination, among other things.
“When a patient presents with neurological symptoms, neurologists will generally explore three main factors to determine the next steps, says Dr. Malkin. “First, they consider whether there is a lesion, or whether the patient’s symptoms are unrelated to the nervous system. Next, if there is a lesion, they need to know where it is, which can be determined by a neurological examination and scans such as a CT scan and/or an MRI. Lastly, they will want to know the type of lesion it is, which is determined from the scan taken as well as by examining the patient’s history and symptoms, while ruling out other lesions such as an abscess from an infection or a blood clot.”
Types of Tumors
There are more than 100 types of brain tumors, but to put it in simple terms, Dr. Malkin identifies three main types: primary benign tumors, primary malignant tumors and metastatic tumors, which occur when cancer cells from other organs spread to the brain through the blood.
Metastatic brain tumors are the most common of all brain tumors, says Dr. Malkin. Of these, the majority originate either from cancers that are highly prevalent, such as lung and breast cancer, or from cancers that are more predisposed to spread to the brain, such as melanomas.
Of the benign primary brain tumors, the most common are meningiomas, although Dr. Malkin points out that, technically speaking, these occur in the meninges – the membranes covering the brain and spinal cord – rather than in the brain itself. Of these meningiomas, around 85% are slow growing and generally benign, he adds. They are usually found incidentally, for example, during a scan after an injury or accident. If meningiomas are not causing any symptoms, they will usually just be monitored via MRIs rather than being treated, Dr. Malkin says.
Of the primary malignant brain tumors, the most common are glioblastomas, which grow very quickly, so the sooner they are treated, the better, says Dr. Malkin.
Treatments and New Developments
If any type of tumor is causing symptoms due to pressure or its location, the first step of treatment will be to remove as much of it surgically as is safely possible. The removed tissue will then be sent to a pathology lab to determine if it is malignant or benign, primary or metastatic.
If tumors are found to be malignant, patients will be treated through a combination of radiation and chemotherapy, with the latter typically given as intravenous injections or pills. For metastatic tumors, the radiation treatment might take the form of stereotactic radiosurgery, which is not surgery, but rather a very precise way to treat a tumor with radiotherapy so as to minimize exposure to radiation to the surrounding normal brain.
There are also new, more personalized treatments under development, Dr. Malkin adds. “Many scientists are working to identify the driver mutations that cause tumors to grow, so that medicines may be developed to target these specific drivers. Two patients’ glioblastomas might look the same under the microscope, but have different mutations driving them, so, ultimately, the patients’ treatment post-surgery could be different for each.”
In addition, there is hope on the horizon for a glioblastoma vaccine, which would be particularly beneficial for patients at risk of recurrent brain tumors, says Dr. Malkin. Cleveland Clinic is participating in ongoing clinical trials for the SurVaxM vaccine, with initial phase-2 results showing promise. Dr. Malkin explains the vaccine targets and inactivates a protein called survivin, which is found on the surface of 80% of glioblastoma cells and is needed for the cells to multiply.
“Given these significant developments in the field, and considering that fewer than 1% of brain tumors are cancerous, patients should not be overly scared to flag any unusual symptoms with their doctors so they can be evaluated as soon as possible,” Dr. Malkin concludes.
