Osteosarcoma overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Suveenkrishna Pothuru, M.B,B.S. [2]
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Osteosarcoma Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Osteosarcoma overview On the Web |
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American Roentgen Ray Society Images of Osteosarcoma overview |
Overview
Bone cancer is a malignant (cancerous) tumor of the bone that destroys normal bone tissue. Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. It is a malignant tumor that is characterized by the direct formation of bone or osteoid tissue by the tumor cells. Malignant tumors that begin in bone tissue are called primary bone cancer. Osteosarcoma may be classified according to the World Health Organization’s histologic classification of bone tumors into three groups. The osteosarcomas may be localized at the end of the long bones (commonly in the metaphysis). Most often it affects the upper end of the tibia, humerus, or lower end of the femur. On gross pathology, areas of bone formation, hemorrhage, fibrosis, and cystic degeneration on cut surface are characteristic findings of osteosarcoma. On microscopic histopathological analysis, presence of osteoid within the tumor, pleomorphic cells, anaplastic cells, and atypical mitoses are characteristic findings of osteosarcoma. There are no established causes for osteosarcoma. The common risk factors in the development of osteosarcoma are radiation to bones, alkylating antineoplastic agents, Paget disease, multiple hereditary osteochondromas, fibrous dysplasia, Bloom syndrome, Rothmund-Thomson syndrome, and Li-Fraumeni syndrome. Common complications of osteosarcoma include pathologic fracture and metastasis. The most common symptoms of osteosarcoma include bone pain that may be worse at night, swelling, and redness at the site of the tumor. On x-ray, osteosarcoma is characterized by medullary and cortical bone destruction, periosteal reaction, tumor matrix calcification, and soft tissue mass. On MRI, osteosarcoma is characterized by intermediate intensity of soft tissue and low signal intensity of ossified components on T1. High signal intensity of soft tissue and low signal intensity of ossified components on T2. The predominant therapy for osteosarcoma is neoadjuvant chemotherapy (chemotherapy given before surgery) followed by surgical resection. The most common drugs used to treat osteosarcoma are cisplatin, doxorubicin and high-dose methotrexate.
Historical perspective
Classification
Osteosarcoma may be classified according to the World Health Organization’s histologic classification of bone tumors into three groups: central (medullary) tumors, surface (peripheral) tumors, and extraskeletal tumors.[1]
Pathophysiology
The osteosarcomas may be localized at the end of the long bones (commonly in the metaphysis). Most often osteosarcoma affects the upper end of the tibia, humerus, or lower end of the femur. On gross pathology, areas of bone formation, hemorrhage, fibrosis, and cystic degeneration on cut surface are characteristic findings of osteosarcoma. On microscopic histopathological analysis, presence of osteoid within the tumor, pleomorphic cells, anaplastic cells, and atypical mitoses are characteristic findings of osteosarcoma. Osteosarcoma may be associated with hereditary syndromes such as Li-Fraumeni syndrome and Rothmund-Thomson Syndrome.
Causes
There are no established causes for osteosarcoma. However, some studies show that an increased level of c-fos proto-oncogene expression can lead to osteosarcoma.
Differential Diagnosis
Osteosarcoma must be differentiated from Ewing's sarcoma, Giant cell tumors, Malignant fibrous histiocytoma, Osteomyelitis, and aneurysmal bone cyst.
Epidemiology and Demographics
Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. It is the 8th leading cancer in children under age 15, comprising 2.4% of all malignancies in pediatric patients and about 20% of all primary bone cancers. The overall incidence of osteosarcoma in U.S. population under 24 years of age are estimated at 0.44 cases for 100,000 individuals.[2] Osteosarcoma is slightly more common in males than in females. Primary osteosarcoma typically occurs in young patients (10-20 years) with 75% occurring before the age of 20. Secondary osteosarcoma occurs in elderly patients.
Risk Factors
The common risk factors in the development of osteosarcoma are radiation to bones, alkylating antineoplastic agents, Paget disease, multiple hereditary osteochondromas, fibrous dysplasia, Bloom syndrome, Rothmund-Thomson syndrome, and Li-Fraumeni syndrome.
Screening
According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for osteosarcoma.[3]
Natural History, Complications and Prognosis
Common complications of osteosarcoma include pathologic fracture and metastasis. Pre-treatment factors that influence outcome of the osteosarcoma are primary tumor site, size of the primary tumor, and site of metastasis. After administration of preoperative chemotherapy, factors that influence outcome of the osteosarcoma are adequacy of tumor resection and necrosis following induction or neoadjuvant chemotherapy. The 5 year survival rate of osteosarcoma after adequate therapy is approximately 60-80%.
Diagnosis
Staging
According to the American Joint Committee on Cancer (AJCC), there are four stages of osteosarcoma based on the size of primary tumor, metastasis, involvement of lymph nodes, and grade of the tumor. For the purpose of treatment, there are only two stages of high-grade osteosarcoma: localized osteosarcoma and metastatic osteosarcoma.
History and Symptoms
The most common symptoms of osteosarcoma include bone pain that may worse at night, swelling, and redness at the site of the tumor. The affected bone is not as strong as normal bones and may fracture with minor trauma (a pathological fracture).
Physical Examination
Physical examination findings will depend on the location of the osteosarcoma. Common physical examination findings of osteosarcoma are localized swelling and tenderness at the site of the tumor.
Laboratory Findings
Laboratory tests for osteosarcoma include complete blood count (CBC), serum alkaline phosphatase and lactate dehydrogenase.
Biopsy
Biopsy of osteosarcoma is important for confirming the diagnosis and for determining the histologic subtype.[4] Biopsy may be performed percutaneously with either a fine-needle, or a wide-bore needle, or through a formal incision.
X Ray
On x-ray, osteosarcoma is characterized by medullary and cortical bone destruction, periosteal reaction, tumor matrix calcification, and soft tissue mass.[5]
CT
CT scan in osteosarcoma may be helpful in biopsy and staging. CT scan adds little to plain radiography and MRI in direct assessment of the tumor.[6]
MRI
On MRI, osteosarcoma is characterized by intermediate intensity of soft tissue and low signal intensity of ossified components on T1. High signal intensity of soft tissue and low signal intensity of ossified components on T2. Considerable contrast enhancement of solid components on T1 contrast.
Other Imaging Findings
Bone scan in osteosarcoma is used to observe abnormal areas of bone and metastasis.[7]
Other Diagnostic Studies
No additional tests are recommended for the diagnosis of osteosarcoma.
Treatment
Medical Therapy
The predominant therapy for osteosarcoma is neoadjuvant chemotherapy (chemotherapy given before surgery) followed by surgical resection. The most common drugs used to treat osteosarcoma are cisplatin, doxorubicin and high-dose methotrexate. Ifosfamide can be used as an adjuvant treatment if the necrosis rate is low. Samarium is a radioactive drug that targets areas where bone cells are growing, such as tumor cells in the bone. It helps relieve bone pain.
Surgery
The mainstay of therapy for osteosarcoma is surgical resection. Rather than using the standard staging system, a simpler system is often used when planning treatment for osteosarcoma. This system divides osteosarcomas into 2 groups: localized osteosarcoma and metastatic osteosarcoma.
References
- ↑ Osteosarcoma. National cancer institute.http://www.cancer.gov/types/bone/hp/osteosarcoma-treatment-pdq#section/_8
- ↑ Osteosarcoma. National cancer institute. http://www.cancer.gov/types/bone/hp/osteosarcoma-treatment-pdq
- ↑ Osteosarcoma. U.S. Preventive Services Task Force.http://www.uspreventiveservicestaskforce.org/BrowseRec/Search?s=osteosarcoma
- ↑ Osteosarcoma. surgwiki. http://www.surgwiki.com/wiki/Diseases_of_bone_and_joints#SURGERY_4
- ↑ Osteosarcoma. Dr Amir Rezaee ◉ and Dr Frank Gaillard ◉ et al. Radiopaedia.org 2015. http://radiopaedia.org/articles/osteosarcoma
- ↑ Osteosarcoma. Dr Amir Rezaee ◉ and Dr Frank Gaillard ◉ et al. http://radiopaedia.org/articles/osteosarcoma
- ↑ Osteosarcoma. Canadian Cancer Society. http://www.cancer.ca/en/cancer-information/cancer-type/bone/diagnosis/?region=bc