Chondrosarcoma are a group of cartilage matrix producing tumors. It is third most common primary bone sarcoma. They can occur primary (De novo) or secondary (as sarcomatous change in osteochondromatosis and enchondroma). It most commonly affects age group 30 – 60 years. They grow very slowly and rarely have distant metastasis or local recurrence (15-25 %).
What is cause of chondrosarcoma?
Etiology of chondrosarcoma (primary) is unknown.
Exostosin gene (EXT 1 & EXT 2) have been identified in conventional chondrosarcoma.
The most common locations of chondrosarcoma are pelvis and long bones of limbs.
How is chondrosarcoma identified?
An individual with Chondrosarcoma presents with dull pain and small palpable tender mass, especially a hard preexisting mass which has rapidly grown in case of peripheral chondrosarcoma.
A successive physical, radiological examination is carried out including plain radiographs, MRI or CT scan followed by Biopsy (Needle). A PET CT is performed to complete staging.
What are the different types & grades of chondrosarcoma?
Different types of chondrosarcoma are:
- a) Conventional (85 %, includes central, peripheral and juxtacortical based on location)
- b) Dedifferentiated (10%)
- c) Mesenchymal (<2 %)
- d) Clear cell (< 2 %).
Central chondrosarcoma are almost always primary whereas Peripheral chondrosarcoma are secondary in origin. Peripheral chondrosarcoma are actually secondary changes in cartilage cap of osteochondroma which is present for a long time (this statement does not necessarily indicate that all osteochondromas need to be surgically removed fearing malignant transformation).
Different grades of Conventional chondrosarcoma are identified which is crucial for treatment and resultant survival.
- Grade I have low cell load and rarely metastasize (< 5 %) with survival rate of 83 %
- Grade II and Grade III are considered high grade with high chance to metastasize and have local recurrences in nearly 60-70 % individuals with survival rate of 64 & and 30 % respectively at 10 years.
- Grade IV: Dedifferentiated chondrosarcoma is a very high grade tumor most commonly seen in pelvis and femur with rapid progression and metastasis, hence associated with bad prognosis (survival rate of 28 % at 10 years). Chemotherapy and high doses (> 60 Cgy) of radiotherapy are the adjuvant therapies that can be attempted, but survival has not improved.
Mesenchymal chondrosarcoma is also a high grade variety of chondrosarcoma which in addition to bone can occur in soft tissues also. No specific etiology has been found. But it has been recently identified to respond to a certain high intensity chemotherapy regimen and radiotherapy thereby increasing survival rate to 89 % at 10 years.
Clear cell chondrosarcoma is low grade variant commonly found in epiphysis of proximal femur, proximal humerus and proximal tibia. Metastasis and local recurrences are very rare but requires long term follow up (even upto 25-30 years) and the results are excellent.
Of note, myxoid chondrosarcoma is a different entity occurring in soft tissues, recently described by WHO as tumor of uncertain differentiation.
How is limb salvage possible in chondrosarcoma?
Surgical removal of primary tumor with wide margins in the most optimal chance of cure in chondrosarcoma.
Grade I chondrosarcoma (Low grade) of long bones of limbs can be at present safely treated with Extended curettage with or without adjuvants (phenol, liquid nitrogen) and filling of cavity with cement or bone graft. The rates of local recurrence are low with this method of treatment for Grade I variant alone. The same tumor in pelvis is preferably treated with surgical removal with wide margins due to the aggressive presentation in this location.
Grade II, Grade III, and Peripheral, Dedifferentiated, Mesenchymal and Clear cell variants of chondrosarcoma are treated with surgical excision with wide margins. Reconstruction of the defect is similar to osteosarcoma and Ewing’s sarcoma. Rehabilitation depends on the type of reconstruction.
Chondrosarcoma of Proximal femur treated with Resection and Bipolar Megaprosthesis
Is there a role for chemotherapy or radiotherapy in chondrosarcoma?
Chondrosarcoma is often regarded resistant to both chemotherapy and radiotherapy. Newer studies have shown some improvement with chemotherapy and radiotherapy in mesenchymal type.
In dedifferentiated type, chemotherapy has limited palliative role.
How often should I visit the doctor?
The individual is followed up every 3 months for the first 2 years, followed by 6 months every 3 years (aggressive monitoring of the patient until 5 years).
Metastasis is more common in lungs. It is rare in grade I chondrosarcoma and clear cell chondrosarcoma, but 10 % of high grade variants of chondrosarcoma individuals present with lung metastases. This can be treated with surgical removal depending on the number and size of nodules in lung. Metastases occurring during follow up will also be treated in the same manner.
Local recurrences when identified should be treated with wide excision in high grade variants of chondrosarcoma which provides a survival rate of 50-60 % at 10 years. In contrast, local recurrences in grade I chondrosarcoma in long bones of limbs can be treated safely with extended curettage and does not affect survival.