What are Brain and Spine Tumors?
Brain and spinal cord tumors are abnormal growths of tissue found inside the skull or the bony spinal column, which are the primary components of the central nervous system (CNS). There are two general types of tumors found: benign tumors are noncancerous (do not spread), and malignant tumors are cancerous and have the ability to spread, or have spread from somewhere else.. Benign tumors are generally slow growing, with distinct borders that can be cured by surgical excision. The Central Nervous System (CNS) is housed within rigid, bony quarters of the skull and spinal column, so any abnormal growth, whether benign or malignant, can place pressure on sensitive tissues and impair function.
It is important to understand the source of the tumor and whether a tumor is benign or malignant. Tumors that originate from the tissues of the nervous system are called primary tumors. Primary tumors can be of the malignant or benign variety. Most primary tumors are caused by out-of-control growth among cells that surround and support neurons, such as astrocytomas; a broad class of common primary brain tumors. In a small number of individuals, primary tumors may result from specific genetic disease (e.g., neurofibromatosis, tuberous sclerosis) or from exposure to radiation or cancer-causing chemicals. The cause of most primary tumors remains a mystery. Tumors that originate from different parts of the body (e.g. lungs) and spread to the nervous system are called metastatic tumors (to the brain or spinal column). Occasionally, a metastatic brain tumor that is discovered in the brain or spine is the first indication that there is cancer in another part of the body. The most common brain metastatic tumors are cancer of the lung (about half of all metastatic brain tumors), skin, breast, and gastrointestinal tract. Treatment of metastatic tumors focuses on the treatment of cerebral edema, headache, and seizure. Multiple factors, such as number and size of the lesions, location, status of the main disease, and patient life expectancy are considered before surgery is offered.
Symptoms of brain tumors vary and can include headaches, seizures, nausea and vomiting, vision or hearing problems, and behavioral, cognitive, motor, and balance problems. The symptoms related to spine tumors can vary from local pain to pain that shoots down an arm or leg. There may also be additional symptoms, such as weakness, loss of extremity sensation, or bowel and bladder control problems. The first test to diagnose tumors is a neurological examination. Special imaging techniques (Computed Tomography - CT, and Magnetic Resonance Imaging - MRI, Positron Emission Tomography - PET) are also often employed, as are laboratory tests including the EEG and spinal tap.
MRI scan is a test using magnetic fields (no radiation) to make computerized images of the brain or spine and detect tumors.
CT scan is a three-dimensional x-ray that takes series of detailed pictures.
PET scan involves injection of a radioactive glucose substance followed by imaging. Cancer cells react to the glucose and provide information about the level of metabolic activity. PET scan can be used to detect cancer metastases.
Common Tumor Types
While there are many potential types of tumors, including benign or malignant, primary or metastatic, there are several more common types of tumors that are briefly outlined below.
Glioblastoma Multiforme (GBM)
GBM is the most common and malignant of the glial tumors (Figure 1) that account for about 60% of all primary brain tumors diagnosed in adults older than 50 years. Symptoms depend on the size and location of the tumor. The standard treatment has been unchanged for many decades; surgical resection to resect as much tumor as safely as possible followed by radiation and chemotherapy. Unfortunately, even if the most aggressive treatment is attempted, the prognosis is usually unfavorable. There are few promising therapies being developed for GBM treatment. One such experimental treatment is a vaccine therapy, which in combination with chemotherapy, could double the average survival for the patients. Tumors express certain receptors and if a tumor over-expresses the receptor called EGFRvIII, the patient is more responsive to the chemotherapy treatment. This vaccine targets EGFRvIII protein and strengthens the immune response in fighting the tumor.
Figure: Left Temporal Glioblastoma Multiforme
This type of tumor arises from the meninges; membranes that surround the brain and spinal cord. The majority of these tumors are benign grow very slowly, and may never require any treatment. If treatment becomes necessary, open surgery has long been considered as the standard choice. These recommendations have been changed since introduction of stereotactic radiosurgery as a noninvasive treatment alternative for these tumors. With 95% / 5-year control rate and low complication rate, radiosurgery is the new “gold standard” treatment for meningiomas. Moreover, in the publication by Colombo et al. (Neurosurgery, 2009) it was described that the use of the CyberKnife expanded indications for radiosurgery to include more that 30% of patients that could not have been treated with framed-based radiosurgery systems (e.g. LINAC, gamma knife).
Acoustic Neuromas are benign tumors of the eighth cranial nerve; the vestibulocochlear nerve. The typical location is the angle between the cerebellum and the pons in the posterior fossa. Symptoms include hearing loss or deafness, tinnitus, a loss of balance, but unilateral hearing loss usually is the most common symptom present at the time of diagnosis. Rarely are acoustic neuromas associated with Neurofibromatosis Type II; a rare genetic condition. Patients with Neurofibromatosis Type II develop tumors on both auditory nerves. Treatment depends on the tumor size, age, and clinical status of the patient. The goal is to eliminate the tumor while preserving neurological function. If surgery is necessary, BNA surgeons have options to offer to patients, including microsurgical removal or stereotactic radiosurgery.
Pituitary Adenomas are tumors located next to or within the pituitary gland. Almost all pituitary adenomas are benign. The symptoms depend on tumor size and the hormone it secrets. The surgical removal of pituitary tumors is performed via one of two main approaches: craniotomy or transspenoidal.
Click this link to read more about this type of surgery.
Cranial Extensions of Head and Neck Cancers
Squamous cell and basal cell tumors that originate in the orbits, salivary glands, oral cavity, larynx, pharynx, sinuses, and other locations can lead to intracranial extensions of tumor. These tumors tend to spread into the skull base and ultimately, the brain. Symptoms are site-specific and mainly depend on the adjacent structures.
Surgical resection of these tumors requires a multidisciplinary approach and neurosurgeons that are experienced in skull base surgery. Recent advances in endoscopic techniques have made possible less invasive access to these tumors and have had a dramatic impact on overall outcomes by reducing mortality, preserving neurological functions, and improving overall prognosis. Many tumors that were previously deemed inoperable are successfully treated using such minimally invasive techniques.
Is there any treatment?
The three most commonly used treatments are surgery, radiation, and chemotherapy. Doctors also may prescribe steroids to reduce the swelling inside the CNS. Surgery is the time-honored technique to accomplish several very important objectives. To establish or confirm the diagnosis is the most important initial objective as it drives treatment strategies and gives important prognostic information to the patient and family. Diagnosis can be accomplished through a biopsy, excision (partial removal of the tumor), or resection (total removal of the tumor). Ideally, the tumor can be removed in its entirety and at the same time a diagnosis can be made.
Craniotomy and Tumor Removal
Craniotomy is a brain operation during which a neurosurgeon makes an opening in the skull bone to remove a brain tumor. The incision is made over the area of the brain tumor. It can be performed under local or general anesthesia. The maximal tumor removal (if possible) is the best treatment for prolonging survival and, in case of benign tumors, may be curative.
Minimal Access Neurosurgical Techniques, in conjunction with advanced intraoperative image-guidance technology, are used to reduce incision and craniotomy sizes to the smallest possible and to optimize the accuracy and safety of neurosurgery. These techniques allow surgeons to navigate as safely as possible to the tumor or lesion. The use of intraoperative MRI allows neurosurgeons to assess tumor resection in a real-time during surgery and increase safety and the potential to maximize resection of the tumor.
Minimal access surgical approaches allow for safer surgery, earlier and optimal recoveries, and shorter hospital stays. BNA neurosurgeons utilize a "minimal shave" technique for scalp incisions where possible. Despite being able to remove a tumor entirely, it is important to understand that, except in highly unusual circumstances, malignant tumors cannot be cured through surgery, chemotherapy or radiation; the growth can only be stabilized or controlled. A decision for the most appropriate treatment option(s) is made depending on the tumor location, imaging characteristics, patient’s health, age, and wishes.
This type of surgery is performed using an endoscope to visualize the tumor in the brain or spine to allow minimally invasive access to some lesions. The entire operation is performed through a tine hole usually in combination with a surgical microscope. This combination allows neurosurgeons to perform an operation deep within the brain and skull base. A small incision site and minimal trauma to the surrounding tissues results in a shorter hospital stay and quicker return to normal activities for patients. These are just a few of the advantages of this type of minimally invasive surgery.
Click this link to read a case report.
For selected patients with tumors, or other pathological conditions, in highly functional parts of the brain (also known as ‘eloquent’ regions of the brain, such as motor, sensory, and speech areas), Boulder Neurosurgical Associate (BNA) surgeons and their team perform a specialized type of surgery called Awake Craniotomy. Patients are lightly sedated during the initial portion of surgery, and awakened when the brain is exposed. Depending on the region of the brain and the lesion, different electrical or cognitive tests are performed to allow the surgeon to carefully ‘map’ the selected region of the brain, thus ideally identify the safest possible route and region of resection. As the brain has no pain receptors, this is a pain-free and comfortable procedure that adds safety to certain craniotomies if necessary. A patient is kept asleep for all other parts of the operation. It is important to understand that a majority of cases do not require awake craniotomy and only your surgeon will identify if you may benefit from this specialized procedure.
Click this link to download a PDF with more information about more about the principles of awake craniotomy that were established more than 50 years ago.
Radiation therapy is often used alone or as an adjunct to surgery. It can be done either before, or ideally, after the surgery. Radiation works by halting the growth of the rapidly growing tumor cells, while to a lesser extent affecting surrounding normal brain cells. It can be used in both benign and malignant tumor treatment strategies, but is usually associated with side effects. In order to minimize such side effects and precisely deliver radiation to the tumor, neurosurgeons at Boulder Neurosurgical & Spine Associates (BNA) often employ the newest radiosurgical treatment technology called CyberKnife.
Chemotherapy works by taking a medication (usually by vein or mouth) that specifically targets tumor cells and causes their dysfunction or death, while minimally affecting normal cells of the brain. Chemotherapy does not have a role in benign tumors.
Intraoperative Neuromonitoring (IOM) is a technique that monitors the patient’s brain tissue and associated functions at risk during surgical interventions. It is becoming the standard of care procedure throughout the country to ensure patient safety. Electrical stimulation allows the surgeon to identify the safest possible route and region of resection. IOM identifies early problems that can be reversed if addressed immediately. The cranial nerves along with sensory and motor pathways are generally monitored and supplementary modalities (e.g. Brainstem Auditory Evoked Potentials, EEG, Electrocorticography and Motor Mapping) maybe be added depending on the procedure and structures at risk. The surgeon identifies patients that may benefit from this specialized procedure and always provides the safest possible surgical management.
What is the prognosis?
Symptoms of brain and spinal cord tumors generally develop slowly and worsen over time unless they are treated. The tumor may be classified as benign or malignant and given a numbered score that reflects how malignant it is. This score can help doctors determine how to treat the tumor and predict the likely outcome or prognosis for the patient. Every patient and family wants to know what the prognosis is. Unfortunately, this is highly variable depending on many different factors, most importantly - the diagnosis (what type of tumor it is), patient’s overall health and if the tumor has spread. Prognosis can range from several weeks to several years to live a full lifetime with the tumor (and ultimately dying from other causes!).
Accurate statistics for the frequency and outcome of brain tumors are not available, and those that are available are often quite variable. It is estimated that the incidence rate of all brain and central nervous system tumors is 16.5 cases per 100,000 person per year. An estimated 51,410 new cases of brain and central nervous system tumors were expected to be diagnosed in the United States in 2007 (Central Brain Tumor Registry of the United States). The five-year relative survival rate following diagnosis of a primary malignant brain and central nervous system tumor is 28.8% for males and 31.6% for females (1973–2004 data).
The various types of brain tumors occur with different frequency in children and in adults. The most common childhood tumors are: astrocytoma, medulloblastoma, and ependymoma. The most common types of adult tumors are: metastatic tumors from the lung, breast and melanoma, glioblastoma multiforme, anaplastic astrocytoma, and meningioma.
What research is being done?
Physicians at Boulder Neurosurgical & Spine Associates have initiated a multicenter clinical study in collaboration with medical centers from Stanford University, Besta Neurological Institute in Milan, and Rocky Mountain CyberKnife Center, to evaluate survival and treatment failure patterns following CyberKnife radiosurgery for newly diagnosed and recurrent glioblastoma multiforme (GBM). Click this link to download a PDF to read more about the results of this study.
Researchers are also studying brachytherapy (small radioactive pellets implanted directly into the tumor) and advanced drugs and techniques for chemotherapy and radiation therapy. Most of these advanced techniques are used in conjunction with surgery. In experimental gene therapy for brain and spinal cord tumors scientists insert a gene to make tumor cells sensitive to certain drugs, to program the cells to self-destruct, or to instruct the cells to manufacture substances to slow their growth. Scientists are also investigating why some genes become cancer-causing. Since tumors are more sensitive to heat than normal tissue, research scientists are testing hyperthermia as a treatment by placing special heat-producing antennae into the tumor region after the surgery. In immunotherapy, scientists are looking for ways to duplicate or enhance the body's immune response to fight against brain and spinal cord cancer. Most of these novel techniques could involve into new revolutionary treatments in the nearest future, but currently the traditional therapies – surgery, radiation and chemotherapy – are the only time-proven treatment methods.
BNA Tumor Program