4.3.4 Osteosarcoma
Osteosarcoma（osteogenic sarcoma）is the most common malignant bone tumor with common sites being the growing region of a bone，especially around the knee.It affects mostly young people between the ages of 10 and 20.It is also common in people over age 60.（Fig.4-5）
Fig.4-5 Osteosarcoma
The cause remains unknown.In some cases，osteosarcoma runs in families.At least one gene has been linked to an increased risk.This gene is also associated with familial retinoblastoma，a cancer of the eye that occurs in children.
Early complaint of pain is often described as an intermittent and dull aching.Night pain is common.As the disease rapidly progresses，the pain increases in intensity and duration.Other symptoms include weight loss，general malaise，and loss of appetite（anorexia）.
Bone biopsy，X-ray films，bone scan，and MRI are the most common methods used to confirm the diagnosis and determine the location and size of the tumor.
Treatment includes radiation，chemotherapy，and surgery to remove the tumor.Patients who respond well to this combination therapy may not lose the extremity to amputation（which has historically been the treatment of choice）.The prognosis for osteogenic sarcoma has improved with combination therapies.Treatment usually starts after a biopsy of the tumor is done.Before surgery to remove the tumor，chemotherapy is usually given.This can shrink the tumor and make surgery easier.It may also kill any cancer cells that have spread to other parts of the body.In most cases，surgery can remove the tumor while saving the affected limb.This is called limb-sparing surgery.In rare cases，amputation is necessary.
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Task 6 Select the best answer according to the text.
1.The most common malignant bone tumor is________.
A.osteosarcoma
B.osteoma
C.osteochondroma
D.chondrosarcoma
2.Retinoblastoma is a cancer of the________that occurs in children.
A.bone
B.skin(https://www.daowen.com)
C.eye
D.muscle
3.The word“intermittent”means________.
A.acute
B.chronic
C.on-again
D.instant
4.________means removal of the extremity.
A.Chemotherapy
B.Amputation
C.Biopsy
D.Prognosis
5.A word that has the same meaning as“shrink”is________.
A.spread
B.remove
C.eradicate
D.dwindle