Chordomas are rare primary tumors of the bones. They can be found anywhere from the base of the skull to the coccyx (tailbone), but most commonly develop in the cervical and sacral spine. These tumors account for only three percent of all bone tumors and 20 percent of all primary spinal tumors. Approximately 300 new cases are diagnosed each year in the United States. Half are found in the sacrum and 30 percent are located in the clivus, which is a bone in the skull behind the nasopharynx and in front of the brainstem.
These tumors develop from cells present during the embryonic development of the spine called the notochord. Chordomas appear benign (non-malignant) when studied with a microscope. However, due to the inherent proximity to the spinal cord, their invasive nature, and rate of recurrence, they are considered malignant.
Chordomas tend to grow slowly, but will infiltrate surrounding tissues rather than metastasizing to distant locations. In the event that a chordoma does begin to metastasize, the organs at highest risk for secondary tumor growth are the lymph nodes, the lungs, and the liver. In surgical resection of these masses, incomplete removal of the tumor volume increases the risk of recurrence in the tumor bed.
Chordomas are, for the most part, considered to be a sporadic tumor. Rare incidents of multiple affected family members have been reported in families with tuberous sclerosis, and certain types of childhood brain tumors. However, there are no known causes or risk factors. Chordomas tend to occur slightly more frequently in males with a median age of diagnosis of 49 years for a clival chordoma, and 69 years for sacral chordoma.
The signs and/or symptoms of a chordoma will greatly depend on the location of the tumor as the development of it will affect the organs in closest proximity. In cervical chordoma (growth in the cervical spine), a patient might experience head and/or neck pain, neurological changes, diplopia (double vision), paralysis of facial muscles, and/or tingling/numbness of upper extremities. In sacral chordoma (growth in the sacral spine) a patient might first notice a lump. However, in some cases, an individual may experience pain, tingling, numbness, or weakness of the lower extremities.
Chordomas themselves do not show up well, but the bone damage may be seen on X-rays. X-rays of the sacrum are often difficult for doctors to interpret.
These images are plain X-ray imaging. These are the first images a physician might order for assessing a patient.
These are Computed Tomography (CT) images typically ordered after finding reasonable concern on a conventional X-ray. These images may also help in the treatment planning of radiation therapy.
These images are Magnetic Resonance Images (MRI scan). This type of scan might also be ordered by a physician to further investigate and plan treatment for the mass.
*Images courtesy of http://orthoinfo.aaos.org/
The primary treatment option for a chordoma is surgery unless restricted by critical structures near the tumor. Chemotherapy will, in most cases, be utilized as a treatment option if the primary tumor has metastasized. Radiation therapy is the third treatment option for a chordoma patient.
The location of chordomas at the base of the skull complicates treatment because of their proximity to the brain stem, cranial nerves, and the pituitary gland.
Proton therapy offers an advantage over conventional radiation therapy as the characteristics of a proton beam offer the capacity for increased accuracy, which is very important when treating around critical structures such as optic nerves, brain stem or the spinal cord. Proton therapy is able to provide a higher dose of radiation than conventional radiation while preserving these critical structures.
A major consideration for treatment of chordoma is the patient's quality of life during and following treatment. With proton therapy, the reduced radiation exposure to healthy tissues and critical structures translates to significant improvements in the daily life of the patient.
Chordomas are malignant and potentially life-threatening tumors. Currently, the median survival rate in the United States is approximately seven years. However, advances in treatment techniques over the past two decades have increased survival rates and improved chances of a cure.
According to The Chordoma Foundation, the overall survival rate of five years is 68 percent and at 10 years is 40 percent. Although complete surgical resection offers the best chance for long-term survival, in many cases, radiation therapy can also prolong survival.
Proton therapy is a successful treatment option for chordomas because proton therapy offers the flexibility of increased tumor doses combined with a high level of accuracy to avoid dosing healthy tissues with unnecessary radiation.