Giant Cell Tumors
Giant cell tumor generally refers to a bone tumor and is typically found in the end of arm and leg bones.
Giant cell tumor of the bone is also referred to as an osteoclastoma as it contains a large number of giant cells resembling a type of bone cells called osteoclasts. Half of all giant cell tumors occurs in the knee, at the lower end of femur (thigh bone) or upper tibia (one of the bones of the lower leg). The tumor is usually located eccentrically and often causes expansion of the bone end. The tumor destroys the bony structure and thus could lead to fractures, even in the absence of stress. Other giant cell tumors can occur in virtually any other bone, including the sacrum, pelvis, and small bones of hands and feet. The growth of this tumor is variable and unpredictable. It is considered to be benign, but can recur following surgical removal. It can also have pulmonary metastases that are mostly curable. Some of the giant cell tumors may change into malignant sarcomas, especially when they recur after high-dose radiation treatment.
Giant cell tumor of tendon sheath
Giant cell tumor of tendon sheath is also referred to a localized nodular tenosynovitis. It usually occurs as single, painless mass that grows slowly. It is mainly found in the wrist and fingers. These are benign growths that can be easily excised (surgically removed). This type is not discussed further in this entry.
Giant cell tumor of bone is mostly seen in adults between the ages of 20 and 40 years. It is slightly more common among women than men and is seen in Asians more than other ethnic groups. It is very uncommon in children.
Causes and symptoms
The cause of giant cell tumors of bone is unknown.
The following symptoms may be seen in patients with giant cell tumors:
- Pain: As this tumors mainly occurs in the joints, arthritic pain is usually the first symptom.
- Swelling: Giant cell tumor causes enlargement of the bone and, as it grows, the patient may find a swelling at the site of the tumor.
- Fracture: Giant cell tumors destroy the surrounding bone and, unlike other bone cancers, fractures are common as the tumor grows. Initially the patient may have a sore or painful joint and the fracture could make it suddenly, severely painful.
Typically the patient with giant cell tumor will go to the doctor because of pain. The doctor will perform routine physical tests and test the affected area for tenderness, swelling, warmth, redness, and mobility. An x ray of the affected area will be obtained. Certain other imaging tests could be done, including magnetic resonance imaging (MRI) and computed tomography (CT scan) to see extent of growth. CT scan of the chest will also be done to test for metastasis to the lungs. An isotope scan may be also done to test for extent of damage. These techniques are noninvasive and can be performed within a day. A surgical biopsy is always done either before or during surgical removal of the tumor. The biopsy determines whether the tumor is malignant and identifies the stage of the tumor. This may done under either local or general anesthesia, depending upon the location of the tumor and the condition and age of the patient.
Clinical staging, treatments, and prognosis
As of 2001 no satisfactory method for grading the tumor into either benign or malignant was available. Most giant cell tumors are initially classified as benign (grade 0). The tumor may progress in three stages. Stage 1, or latent stage, consists of a very slow growing tumor. It is well demarcated and there is little destruction of the outer surface of the bone. Stage 2, or the active stage, is the most commonly found stage. In this stage the tumor grows more steadily and the cortex (or outer layer of the bone) is lost. Stage 3 is the aggressive stage and accounts for about 20% of all giant cell tumors. In this stage the tumor grows rapidly and extends beyond the bone into the soft tissue. This stage is also associated more frequently with fractures.
Treatment of giant cell tumors is mainly surgical. Most stage 1 and 2 and some stage 3 tumors are treated by aggressive curettage, and the bone may be treated chemically and filled with cement. In some stage 2 and most stage 3 lesions the affected section of the bone may have to be removed (en bloc resection). In very rare cases the tumor may be so expanded that amputation may be necessary. Radiation is used to treat giant cell tumors in a location difficult to treat surgically. Chemotherapy has not been shown to be effective against giant cell tumors.
Prognosis following resection is excellent, with less than 5% chance of recurrence. When the tumor is removed by curettage followed by aggressive chemical treatment, there is a 5-10% chance of local recurrence. When the tumors recur locally it is usually within three years of surgical removal and the patient needs to be monitored closely during this time. A small percentage of giant cell tumors can metastasize to the lungs. The metastases can be removed surgically and most can be cured.
When a rare case of malignant sarcoma develops from a giant cell tumor, it is treated aggressively by surgery. In these cases prognosis is poor and long-term survival rate is as low as 20-30%.
Alternative and complementary therapies
There are no alternative or complementary therapies available for giant cell tumors.
Coping with cancer treatment
As the treatment for giant cell tumors is mainly surgical, physical therapy with strengthening exercises to restore range of motion is extremely important. If amputation is required resulting psychological effects will also have to be addressed, especially as this disease occurs in adults who are physically and sexually active.
As of 2001 there were no ongoing clinical trials by any major agencies specifically for treatment of giant cell tumors.
As the cause of giant cell tumors is not known, there is no known method for prevention. When adults in the age group of 20-40 years notice pain and swelling in the joints, prompt radiological evaluation could identify giant cell tumors in early stages and lead to a complete cure.
Whenever a giant cell tumor is suspected, a chest CT scan should also be performed to check for metastasis to the lungs. During pregnancy the tumor can grow more rapidly, in which case it may be better to wait to perform surgery until the baby can be safely delivered by induction. If a patient with giant cell tumor suffers a fracture at the affected area, it may be best to wait until the fracture is healed before performing the surgery.
Campanacci, Mario. Bone and soft tissue tumors. New York:Springer-Verlag Wien Publishing, 1999.
DeVita, Vincent T., Samuel Hellman., and Steven A. Rosenberg, eds. Cancer, Principles and Practice of Oncology. Philadelphia: J. B. Lippincott Company, 1993.
Blackley, H. R. et al., "Treatment of giant cell tumors with curettage and bone grafting." Journal of Bone and Joint Surgery, American, 81, no. 6: (1999) 811-20.
The American Academy of Orthopaedic Surgeons. 6300 N.River Road, Suite 200, Rosemont, IL 60018. (847) 823-8125. <http://www.aaos.org>
Malini Vashishtha, Ph.D.
—Commonly known as CT or CAT scan. It uses a rotating beam of x ray to get internal images of the body from different angles. During this test a harmless dye may be injected to increase contrast between normal and abnormal tissues.
—Surgical method in which a tumor is scraped away from the healthy tissue.
Magnetic resonance imaging
—Also referred to as MRI. A procedure using a powerful magnetic field and radio waves to produce images of internal organs. MRI images can be used to look at soft tissues like muscle and fat.
—Uncommon, malignant tumors that begin in bones, or soft tissues such as muscle or fat.