Sarcomas Health Article

Definition

A sarcoma is a malignant tumor (neoplasm), or cancer. Certain sarcomas characteristically spread throughout the body. The word "sarcoma" has its etiology in a Greek word whose definition is "fleshy." Tumors come from the mesenchymal tissue, from which connective tissues, blood, lymphatics, bone, and cartilage come. The blood carries sarcomas throughout the body into neighboring tissue, or via the bloodstream. Frequent sites of extension of the tumors are the lung, the liver, and the brain.

Description

When the original site of the cancer is the bone, there is a primary bone cancer. The tumor originates in or near a bone. Most primary bone tumors are benign, and the cells that compose them do not metastasize (spread) to nearby tissue or to other parts of the body.

Sarcomas account for fewer than 1% of all cancers diagnosed in the United States. They can infiltrate nearby tissues, enter the bloodstream, and metastasize to other bones, tissues, and organs far from the site of the original malignancy. Malignant primary bone tumors are characterized as either:

• cancers that originate in the hard material of the bone
• soft-tissue sarcomas that begin in blood vessels, nerves, or tissues containing muscles, fat, or fiber

Types of bone tumors

Osteogenic sarcoma, or osteosarcoma, is the most common form of primary bone cancer, accounting for about 5% of all cancers in children. Every year, 900 new cases of osteosarcoma are diagnosed in the United States. The disease usually affects teenagers and young adults, and is almost twice as common in males as in females.

Osteosarcomas grow very rapidly. Although they can develop in any bone, but they are most often seen along the edge or on the end of one of the fast-growing long bones that support the arms and legs. Approximately 80% of all osteosarcomas develop in the distal femur or in the proximal tibia (parts of the upper and lower leg nearest the knee). The next likely location for an osteosarcoma is the proximal humerus (the bone of the upper arm closest to the shoulder).

Ewing's sarcoma is the second most common form of childhood bone cancer. Accounting for less than 5% of bone tumors in children, Ewing's sarcoma usually begins in the soft tissue or nerves. It rapidly metastasizes to the lungs, and may metastasize to bones in other parts of the body.

Ewing's sarcoma occurs most frequently in children aged 11–15. It is more often diagnosed in taller teens. Slightly more males than females develop common bone cancer—but this type is the most frequently found carcinoma in children. The disease is rarely diagnosed in children younger than five and adults older than 30. It primarily affects Caucasians, and rarely occurs in African Americans and native Chinese persons.

Chondrosarcomas are cancerous bone tumors that most often appear in middle age. Usually originating in cartilage in ribs, leg, or hip bones, chondrosarcomas grow slowly. They rarely metastasize to the lungs. It takes years for a chondrosarcoma to metastasize to other parts of the body, and some of these tumors never spread.

Parosteal osteogenic sarcomas, fibrosarcomas, and chordomas are rare. Parosteal osteosarcomas generally involve both the bone and the periosteum, the membrane that covers bones. Fibrosarcomas originate in the ends of the bones in the arm or leg, and then spread to soft tissue. Chordomas develop on the skull or spinal cord.

Osteochondromas, which usually develop between persons aged 10–20 years, are the most common noncancerous primary bone tumors. Giant cell tumors generally develop in a section of the femur near the knee. Giant cell tumors are originally benign, but sometimes become malignant.

Causes and symptoms

The cause of bone cancer is unknown, but the tendency to develop it may be inherited. Children who develop bone tumors are often tall for their age, and the disease seems to be associated with growth spurts during childhood and adolescence. Injuries can make the presence of tumors more apparent, but do not cause them.

A bone that has been broken or exposed to high doses of radiation that has been used to treat other cancers is more likely than other bones to develop osteosarcoma. It should be noted, however, that the amount of radiation in diagnostic x rays poses little or no danger of bone cancer development. A history of noncancerous bone disease also increases bone cancer risk.

Cancer of the eye (retinoblastoma) is a rare tumor of the eye that develops in the cells of the retina, and occurs mostly in patients under five years of age. It is known to be hereditary—the condition is an autosomal-dominant trait.

Both benign and malignant bone tumors can distort and weaken bone, causing pain, but benign tumors are generally painless and asymptomatic.

Patients may feel a lump or mass, but pain in the affected area is the most common early symptom of bone cancer. Pain is not constant in the initial stages of the disease; it is aggravated by activity and may be worst at night. If the tumor is located on a leg bone, the patient may limp. Swelling and weakness of the limb may not be noticed until weeks after the pain began.

Other symptoms of bone cancer include:

• a bone that breaks with minimal trauma, also known as a pathologic fracture
• difficulty moving the affected part of the body
• fatigue
• fever
• a lump or swelling on the trunk, an arm or leg, or another bone
• persistent, unexplained back pain
• weight loss