Chordoma
Overview
Chordoma is a rare slow-growing malignant neoplasm thought to arise from cellular remnants of the notochord. The evidence for this is the location of the tumors (along the neuraxis), the similar immunohistochemical staining patterns, and the demonstration that notochordal cells are preferentially left behind in the clivus and sacrococcygeal regions when the remainder of the notochord regresses during fetal life.
Symptoms
If the chordoma starts in the spine, symptoms may include: * pain * changes in bowel habit * incontinence * impotence * numbness * changes in mobility (movement) If the chordoma starts in the base of the skull, symptoms may include: * headache * double vision * facial pain * changes in hearing * difficulty swallowing.
Causes
Chordomas are believed to develop from pieces of notochord that, for some reason, did not break down as they should. Over many years, these harmless bits of notochord may transform and become cancerous, forming chordomas. The exact cause of chordoma and what increases the risk of developing it is unknown. We do know they are not caused by any injury to the bone, or by an inherited faulty gene.
Diagnosis
Usually you begin by seeing your GP, who will examine you and may arrange any necessary tests or x-rays. For chordomas in the spine, your GP will probably refer you to a specialist surgeon (called an orthopaedic surgeon) who can carry out other investigations. They may also decide to refer you to a specialist hospital or bone tumour centre for further tests. This is because many of the tests for diagnosing bone tumours, such as biopsies, require experience and specialist techniques.
Prognosis
In one study, the 10-year tumor free survival rate for sacral chordoma was 46%. Chondroid chordomas appear to have a more indolent clinical course. In most cases, aggressive surgical resection followed by radiation therapy offers the best chance of long-term control. Chordomas are relatively radioresistant, requiring high doses of radiation to be controlled. The proximity of chordomas to vital neurological structures such as the brain stem and nerves limits the dose of radiation that can safely be delivered. Therefore, highly focused radiation such as proton therapy and carbon ion therapy are more effective than conventional x-ray radiation.
Treatment
There are no drugs currently approved to treat chordoma, however a clinical trial conducted in Italy using the PDGFR inhibitor Imatinib demonstrated a modest response in some chordoma patients.[5] The same group in Italy found that the combination of imatinib and sirolimus caused a response in several patients whose tumors progressed on imatinib alone.