Chondrosarcoma

Chondrosarcoma is a cancer of cartilage-forming cells. It usually arises inside a bone, or on its surface, and it is one of the more common primary bone cancers in adults, where “primary” means it starts in the bone rather than spreading there from elsewhere.

Unlike osteosarcoma, which is largely a disease of teenagers, chondrosarcoma is typically a disease of middle and later life. In a recent series of 109 patients, the median age was 57.

The essentials

If you read nothing else on this page, these are the points that matter most.

1. Grade matters more than anything else. A grade 1 cartilage tumour and a grade 3 one are almost different diseases. Ask what grade yours is. It determines everything that follows.
2. Surgery is the treatment. Conventional chondrosarcoma responds poorly to chemotherapy and radiotherapy. That sounds alarming and is actually the opposite: it means removing the tumour properly can be curative on its own.
3. Low-grade tumours often need less surgery than you fear. In a limb, a grade 1 tumour can frequently be scraped out from inside the bone rather than having a segment removed.
4. Most patients keep the limb. Removing the tumour and reconstructing the defect is the usual approach.
5. Dedifferentiated chondrosarcoma is the serious exception. It is uncommon (1 to 2% of cases) but aggressive, and complete surgical removal is the single most important thing in its favour.

Grade, and why it is discussed so carefully

Grade describes how aggressive the cells look under the microscope. For chondrosarcoma it predicts behaviour better than size, better than site, better than anything else available.

• Grade 1 grows slowly and does not spread to other parts of the body. In an arm or leg it is usually called an atypical cartilaginous tumour rather than a chondrosarcoma at all: the same tumour, renamed to reflect that it is a local problem rather than a life-threatening one.
• Grade 2 is intermediate, and can spread.
• Grade 3 is aggressive, and spreads more readily.

There is an honest caveat worth knowing, because it explains why your case may be reviewed more than once. Grading cartilage tumours is genuinely difficult, and pathologists do not always agree. Published work describes the interobserver variability in grading as high enough to blur the line between low- and high-risk patients. This is precisely why these tumours are reviewed by pathologists who specialise in bone, and why the scan, the biopsy and the pathology are interpreted together rather than any one of them being taken as the final word.

Research is beginning to add molecular tools to this: mutations in genes called IDH1 and IDH2 are found in the majority of chondrosarcomas, and specific patterns appear to carry prognostic information. That work is not yet part of routine care, but it is the direction the field is moving.

Why surgery, and not chemotherapy or radiotherapy

This is the point patients most often have backwards, so it is worth stating plainly.

Conventional chondrosarcoma is relatively resistant to both chemotherapy and radiotherapy. Radiotherapy literature describes these tumours as radioresistant, requiring very high doses to achieve durable control. That is why, where radiotherapy is used at all, it tends to be in sites like the skull base where complete surgical removal is impossible. Chemotherapy has little activity against the conventional form.

At first hearing that sounds like bad news. In practice it means something more useful: the operation is not one part of a package, it is the treatment. Getting it right the first time is therefore what matters most, and it is the reason these tumours should be managed at a unit that does this regularly.

The exceptions are real and specific. Dedifferentiated and mesenchymal chondrosarcoma are the only two subtypes considered potentially chemosensitive; the conventional, clear cell and periosteal forms are not. Both exceptions are dealt with below.

The operation

Low-grade tumours in a limb

For an atypical cartilaginous tumour in a long bone, the tumour can often be removed from within the bone: curettage, meaning it is scraped out, with the cavity then treated and filled. This preserves the bone and the neighbouring joint, and the functional difference compared with removing a whole segment of bone is substantial.

The trade-off is a modest risk of regrowth. In a series of 35 atypical cartilaginous tumours treated by curettage, 4 (about one in ten) came back locally. The detail that matters more: three of those four recurrences came back at a higher grade than the original. That is why follow-up continues after what feels like a minor operation for a tumour that “does not spread”.

Grade 2, grade 3 and dedifferentiated tumours

These require wide resection: the tumour removed in one piece together with a cuff of healthy tissue on every side, following the principle set out in surgery for sarcoma.

How much has to go depends on where the tumour is. In a limb this may mean removing a segment of bone and rebuilding it with an implant, or with bone from elsewhere. Most patients keep the limb. Amputation remains occasionally the better operation, usually when the tumour has grown around the major nerves and vessels so completely that a reconstructed limb would be neither useful nor safe. That is a judgement about what the tumour involves rather than how big it is, and one discussed fully in advance.

Chondrosarcoma of the pelvis is a particular technical challenge, because achieving a clear margin means working around the hip joint, the bladder and bowel, and the major vessels and nerves to the leg. These operations are long, planned in detail, and are among the strongest arguments for a specialist centre.

The margin is what the evidence keeps pointing at

Across the studies on this page, one finding recurs regardless of subtype: whether the margin is clear is the factor most consistently linked to the tumour coming back. In the national registry study of dedifferentiated chondrosarcoma, an incomplete margin more than tripled the risk of local recurrence. In mesenchymal chondrosarcoma the same relationship appeared, and more strongly still. Not having surgery at all carried the worst outlook of any factor examined.

Dedifferentiated chondrosarcoma

This is the form that gives the disease its reputation, and it deserves a straight account.

What it is: a low-grade cartilage tumour in which one area has abruptly transformed into a high-grade sarcoma that is no longer cartilage at all. Under the microscope the two sit side by side with a sharp border between them. It accounts for 1 to 2% of all chondrosarcomas, and most patients are over 50. The commonest sites are the thigh bone and the pelvis, then the upper arm, shoulder blade, ribs and shin.

Why it is so serious: distant spread is common (reported in the range of 40 to 80% of patients) and is frequently already present when the diagnosis is made. Reported five-year survival is about 7 to 24%. In the national registry study, patients who already had metastases at diagnosis had a five-year disease-specific survival of 9.7%, against 37.1% for those whose disease was confined when found.

That contrast carries the most useful message on this page: when this tumour is caught before it has spread, the outlook is meaningfully, if not dramatically, better. Which is an argument for taking a changing cartilage lesion seriously rather than watching it.

What treatment involves. Surgery is central, and the evidence is unusually direct about it: in localised disease, complete removal in one piece with wide margins is described as the principal determinant of control. Radiotherapy did not reduce local recurrence in the registry study.

Chemotherapy is genuinely unresolved, and this is where honesty matters more than reassurance. A systematic review pooled 11 studies and 556 patients with localised disease: five-year survival was 28% with surgery plus chemotherapy against 24% with surgery alone, a difference that was not statistically significant. There was a signal of benefit in the subgroup whose tumour arose on the surface of the bone rather than within it. The authors’ own conclusion was that no conclusion could be drawn either way: neither that chemotherapy helps nor that it does not.

In practice that means the decision is individual, made by the multidisciplinary team, and it is a situation where asking about clinical trials is entirely reasonable. In advanced disease, chemotherapy produces a response in around one patient in five and typically holds the disease for four to five months. That is real but not curative, and worth understanding in those terms.

Two other subtypes worth naming

Mesenchymal chondrosarcoma is rare, tends to affect younger patients, and is defined by a specific gene fusion. It is the other chemosensitive exception: combining complete surgical removal with multi-agent chemotherapy of the kind used for Ewing sarcoma is associated with better disease control, and reported five-year survival is in the range of 55 to 73%, far better than dedifferentiated disease. As elsewhere, an incomplete margin was strongly linked to local recurrence, and patients whose disease had spread at presentation did much worse (five-year disease-specific survival around 20%, against about 80% for those without spread).

Clear cell chondrosarcoma is a rare, slow-growing form that characteristically sits at the very end of a long bone, next to the joint, most often the top of the thigh bone. It can look almost identical to a benign chondroblastoma on X-ray, and it may be present for years before diagnosis. It is treated surgically.

What this means for you

• Ask what grade your tumour is. Grade 1 or an atypical cartilaginous tumour is a local problem that does not spread. Grade 2 and 3 are different conversations.
• Expect surgery to be the main treatment, and expect that to be presented as a good thing rather than a limitation: it is what works in this disease.
• If your tumour is low grade and in a limb, ask whether curettage rather than segment removal is appropriate. It often is.
• Expect follow-up even after a low-grade tumour, because when these come back they can return at a higher grade.
• If you have been told “dedifferentiated”, understand that surgery to remove it completely is the single most important thing, that chemotherapy is a genuine open question rather than a settled omission, and that a clinical trial may be worth asking about.

Everything here depends on establishing exactly which tumour is present, which is decided on tissue reviewed alongside the imaging. The steps are set out in tests and diagnosis, and how a plan is agreed in how treatment is planned. The benign cartilage lesions these tumours have to be distinguished from (enchondroma, osteochondroma and chondroblastoma) are covered in benign cartilage tumours.

If you have been told you may have a cartilage tumour, early contact with a unit that manages these regularly, ideally before a biopsy is taken, is the most useful step.