Cancer Awareness

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Understanding bone cancer

Few things in the world are stronger than bone. According to the American Cancer Society, some bone is able to support as much as 12,000 pounds per square inch, and it can take as much as 1,800 pounds of pressure to break the femur, which is the longest, heaviest and strongest bone in the human body.

Though bone may appear invincible, anyone who has ever suffered a broken bone knows that's not the case. In addition to breaks, bones can fall victim to disease, including bone cancer. Cancers that start in the bone are uncommon, so many diagnosed with bone cancer often have lots of questions about their disease. Gaining a better understanding of bone cancer can help men and women in their fight against the disease.

What is bone cancer?

According to the National Cancer Institute, bone cancer is a malignant tumor of the bone that destroys normal bone tissue. But the presence of a bone tumor does not necessarily mean a person has cancer, as not all bone tumors are malignant and benign, or noncancerous, bone tumors are more common than malignant tumors. Benign tumors do not spread or destroy bone tissue, though they can grow and compress healthy bone tissue.

How do doctors distinguish between the types of bone cancers?

There are different types of bone cancers, and doctors distinguish one from another by determining the type of tissue in which the cancer began. Cancer can begin in any type of bone tissue, including osteoid, cartilaginous and fibrous tissues.

What are some types of bone cancers?

Osteosarcoma is a type of primary bone cancer that arises in the osteoid tissue in the bone. This type of tissue is hard or compact, and tumors that begin in osteoid tissue most often occur in the knee and upper arm.

Chondrosarcoma is another type of bone cancer that begins in the cartilaginous tissue, which is tough and flexible tissue that pads the ends of bones and lines the joints. Chondrosarcoma is typically found in the pelvis, upper leg and shoulder, and a chondrosarcoma that contains cancerous bone cells may be classified as an osteosarcoma.

There are also a family of tumors that may arise in soft tissue, such as muscle, fat, fibrous tissue, or blood vessels, but typically occur in bone. This family of tumors is known as the Ewing Sarcoma Family of Tumors, or ESFTs. These types of tumors are most often found along the backbone and pelvis and in the legs and arms.

What causes bone cancer?

There is no definitive cause of bone cancer, though several factors have been identified as increasing a person's likelihood of developing bone tumors. For example, osteosarcoma occurs more frequently in people who have previously been treated with certain anticancer drugs and those who have undergone high-dose external radiation therapy.

Studies also have indicated that people with hereditary defects of bones are more likely to develop osteosarcoma, as are people with metal implants that were used to treat past bone fractures.

Are there symptoms of bone cancer?

The most common symptom of bone cancer is pain, which may be persistent or unusual near a bone where a tumor is present. But such pain does not necessarily indicate cancer, so men and women dealing with pain in their bones should visit a doctor, who can conduct tests to determine the cause of the pain. Swelling in or near a bone also may be a byproduct of bone cancer.

How is bone cancer diagnosed?

When an individual reports persistent or unusual pain or swelling near a bone to a doctor, that physician will likely inquire about the individual's personal medical history and that of his or her family. A physical examination also will be conducted, after which the doctor may order certain tests.

One of the tests doctors use to diagnose bone cancer is an x-rays of the area, which can provide a depiction of the tumor, including its location, size and shape. Special imaging tests, such as an MRI, a CAT scan, a PET scan, and a bone scan, may also be ordered for patients whose pain is especially unusual or persistent.

A biopsy also may be ordered to determine if cancer is present. During a biopsy, a tissue sample will be taken from the bone tumor to determine if it is malignant or benign. Biopsies of bone tissue are often conducted by orthopedic oncologists.

Some doctors dealing with patients experiencing persistent or unusual pain in their bones may order a blood test to determine if a high level of alkaline phosphatase is present in the blood. High levels of this enzyme are normal in children and adolescents because they are still growing, so parents should know that a high level of alkaline phosphatase in their children's blood does not necessarily mean the child has bone cancer.

More information about bone cancer is available at www.cancer.gov.