Bone cancer destroys healthy bone tissue and forms a malignant bone tumor. While there are many cases of bone tumors, most are not cancerous and do not destroy bone tissue. The American Cancer Society reports that cases of cancerous bone tumors are actually quite rare, accounting for approximately 2,500 diagnoses in 2009, as opposed to lung cancer, which had an approximate number of 220,000 cases diagnosed in 2009.
Symptoms
The most common symptom of bone cancer is pain along the bone. The Mayo Clinic reports that pain can also be accompanied by tenderness, swelling, fatigue, weight loss and the ability to easily suffer bone fractures.
Causes
A specific cause of bone cancer is not known. The American Cancer Society reports that some bone cancer can be caused by defective DNA, which can be inherited. However, it also states that most bone cancers are not caused by inherited DNA defects, but rather by DNA that has changed because of exposure to environmental factors, such as radiation and toxic chemicals, or for no specific reason at all. A type of bone cancer called metastatic bone cancer is caused by cancer cells that have spread to the bone from a cancer in another part of the body. For example, cancerous cells from lung cancer can spread to the bone, where it forms a tumor. Even though the cancer is on the bone, it is not bone cancer, but rather breast cancer that has metastasized, or spread to the bone.
Types
There are a few different types of primary bone cancer. Primary bone cancer is a tumor that begins in the bone tissue. The bones are made up of three different tissues: osteoid, which is the hard tissue also known as "compact" tissue, cartilaginous, which is strong but flexible tissue and fibrous tissue. The tissues make up the bone layer, and inside the bone is a cavity that is filled with bone marrow, which is another type of tissue. The different types of bone cancer are defined based upon the type of tissue they form in. The National Cancer Institute explains that bone cancer that forms in osteoid tissue is called osteosarcoma, which commonly develops in the upper arms and knees. Bone cancer that develops in cartilaginous tissue is called chondrosarcoma, and if often forms in the pelvis, hip joints, shoulder joints and upper leg. The other type of bone cancer is referred to as Ewing's sarcoma, which can begin in other bone-supporting tissues, such as fat, blood vessels and muscles, as well as the bone. The National Cancer Institute reports that Ewing's sarcoma tumors often begin in the arms, legs, pelvis and backbone.
Staging
When one is diagnosed with bone cancer, it is given a stage. The stage of the cancer helps both the doctor and the patient know where the cancer is in its progression, which will help determine the course of treatment. Bone cancer is classified into one of four stages. The Mayo Clinic states that Stage 1 means that the cancer remains in the bone and has not spread to any other areas of the body, and an examination of a biopsy shows that it is not an aggressive type of bone cancer. Stage 2 indicates that while it is still localized to the bone, a biopsy has found it to be an aggressive cancer, meaning it has the ability to grow and spread quickly. Stage 3 bone cancer means it is in more than one area on the original bone, and Stage 4 refers to bone cancer that has spread from the bone into other parts of the body.
Treatment
Once the bone cancer has been diagnosed and staged, the physician will assess which treatment will be more effective in fighting the cancer. The American Cancer Society reports that surgery is the most widely used treatment for bone cancer. Surgery can involve removing the tumor from the bone, along with an area of normal bone tissue. If the surgeon feels that the cancerous cells have spread throughout the bone, then removing the entire bone, such as an arm or part of the leg, may be necessary. Chemotherapy is often used to treat Ewing's sarcoma or osteosarcoma. This treatment involves administering drugs to the patient that travel through the bloodstream to fight the cancer cells. Radiation is not a common treatment for bone cancer, as in order to be effective it needs extremely high doses, and this can damage the healthy tissues in the body that are near the bone.
