In the first place, giant cell tumor (also called “malignant giant cell tumor”) is rare. As a matter of fact, it is much more common in females than males and occurs after bone growth is finished.
Notably, it develops at the extreme end of long bones in proximity to or even being part of the joint. Significantly, 75% of these cancers develop around the knee joint, the sacrum or in the vertebrae. In general, with every recurrence after treatment the new tumor tissue becomes more resistant and difficult to treat.
Initially there is low potential for distant metastases, after the first recurrence there is a 30 to 40% malignant transformation with the potential for distant metastases.
The first symptom is usually joint pain in a mass that is developing in or near a joint. There is joint effusion, a mass at the bone and the range of motion in the affected joint is decreased.
An X-ray suggests the diagnosis to an extent, but this alone is not reliable. A bone biopsy is needed and will help the pathologist to identify the typical giant cell that is found together with other histological characteristics, which confirms the diagnosis.
Bone surgery with a complete removal of the tumor is the treatment of choice. It will cure 90% of this type of bone cancer. Recurrence with this tumor is high, if the surgeon does not remove all cancer. The orthopedic surgeon must remove all of the cancerous tissue completely.
The surgeon achieves this through complete resection, if this is feasible or else by careful curettage and cryosurgery with a probe with liquid nitrogen. This technique of combined curettage and cryosurgery allows the surgeon to eradicate the tumor while preserving joint motion and avoiding amputation or resection. In capable hands as few as only 2% recurrences occur after the first surgery, a 10-fold decrease from the old technique, which had 20 % or more recurrences. Other successful techniques are radiotherapy in a major Cancer Clinic with experience in this rare bone tumor. There were some fears of late malignant complications after radiotherapy in the past, but it turns out that the reoccurrences were due to inadequate dosage of the radiation treatment. Chemotherapy does not work with this type of bone cancer. Rarely an amputation is necessary when the tumor is large and local resection is not feasible.
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