This information has been written for patients, their families and friends and the general public to help them understand more about a rare form of primary bone cancer, known as chordoma. This page will detail what a chordoma is and how a chordoma is diagnosed and treated.

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What is chordoma?

Chordoma is a rare form of primary bone cancer, known to affect only 1 individual per 800,000 people every year (1). They account for less than 5% of all primary bone tumours. Chordomas affect males more commonly than females (1.5:1 male: female ratio). Approximately 60-65 people are diagnosed with chordoma each year in the UK and Ireland. The median age of diagnosis is 58 years and they are very uncommon in patients under 30 years of age (1, 2).

Chordomas most frequently arise in the skull base, along the spine and the sacrum. The different locations of these tumour lead to varying symptoms. This variation of symptoms, and the slow-growing nature of the tumour often make the diagnosis of a chordoma difficult and lengthy.

50% of chordomas are reported in the sacrococcygeal region of the spine, which is the very base of the spine where it connects to the pelvis. A further 35% occur in the base of the skull where the skull meets the spine (known as the spheno-occipital region, often affecting a region of the occipital bone called the clivus) and the remaining 15% present in the vertebral column; which includes all areas along the main length of the spine (2).

This tumour type is thought to develop from tissue known as the notochord (pronounced no-tow-cord). This is the most widely accepted hypothesis, but there is no strong evidence to univocally support this. The notochord is required during embryonic development to form the template of spinal tissue while the baby is in the womb. Over time, this developmental structure is replaced with bone and there is no use for the notochord in adults. Small areas of the notochord are likely to remain into adulthood in many individuals with no effect. However, like any other cell type, these small areas of remaining notochord are capable of being transformed into cancerous cells which grow uncontrollably to form a chordoma tumour (3).

Most chordomas are low-grade tumours, meaning they are slow-growing and unlikely to spread elsewhere in the body (2,4). However, they can become locally aggressive and cause bone destruction in neighbouring areas. If an advanced chordoma does spread (a process known as metastasis), it will most commonly affect the lungs, nearby lymph nodes, the bones, the liver or the skin (5).