Bone Cancer - Primary Bone Cancer

Introduction

Anatomy

Adults have over 200 bones in their bodies.  Your bones vary in size and shape.  Your arms and legs contain long bones.  Vertebrae, series of small bones, make up your spine.  Very small bones form your hands and feet.  Some of your bones have curves, including your ribs and skull.  All of your bones line up and connect to form your skeleton.  In addition to creating your body structure, your bones also produce blood cells, form joints for movement, and protect your internal organs.
 

Your bones are live tissues.  They change and grow like the other parts of your body.  Osteoblasts are bone cells that form bone.  Bone is constantly forming.
 

Most of the bones in your body are composed of the same layered materials.  The periosteum is the outer layer of a bone.  It is considered the life support system for the bone because it provides the nutrient blood for bone cells.  The periosteum produces bone-developing cells during growth or after a fracture.
 

Underneath the periosteum is the cortex.  The cortex is compact bone.  It is hard and solid.  The cortex covers the cancellous “spongy” bone.  The cancellous bone looks like a sponge because it contains many pores.  It can resist the stress of weight, postural changes, and growth.  In many bones, the cancellous bone contains or protects the red marrow or bone marrow.  Red marrow contains developing and mature blood cells.
 

The ends of most bones are covered with cartilage.  Cartilage forms a smooth surface for your bones to glide on during motion.  It also acts as a shock absorber to cushion impacts.
 

Causes

The exact cause of primary bone cancer is unknown.  Cancer occurs when cells grow abnormally and out of control, instead of dividing in an orderly manner.  Inherited genetic changes appear to be associated with some forms of inherited bone cancer.  However, most people that develop primary bone cancer have no known risk factors.

Primary bone cancer originates in the bone.  It is different than metastasized cancer that has spread to the bone from other parts of the body.  There are several different types of primary bone cancers.  The majority of primary bone cancers are sarcomas.  The most common types include osteosarcoma, chondrosarcoma, and Ewing tumors.

Osteosarcoma is the most common type of primary bone cancer.  It most frequently occurs in young people and older adults.  Chondrosarcoma is cancer of the bone cartilage.  It is the second most common type of primary bone cancer and usually develops in adults.  Ewing tumor, also called Ewing sarcoma, is the third most common type of primary bone cancer.  It most frequently originates in the arms and legs.  Ewing tumors are more common among children, young adults, and Caucasians.

Symptoms

Diagnosis

Bone pain and swelling are more frequently due to other conditions that are less serious than cancer.  However, it is important to have your symptoms promptly evaluated by a doctor.  Primary bone cancer that is diagnosed and treated before it has spread has the best outcomes.

Your doctor will review your medical history, perform a physical evaluation, and conduct some tests.  In most cases, a biopsy is necessary to confirm the diagnosis of primary bone cancer.  A biopsy involves obtaining a tissue sample for evaluation of cancer or abnormal cells.

Blood tests are used to test for biological markers, substances that are produced by some people with primary bone cancer.  Bone specific alkaline phosphatase (BSAP) is an enzyme produced by osteblasts during bone formation.  Cancer causes an increase in bone cell formation.  If cancer is present, the BSAP levels may be elevated.  However, BSAP levels are not useful for separating if the overproduction is a result of primary bone cancer or metastasized bone cancer.

Common imaging tests for evaluating cancer in the bones include X-rays, bone scans, and skeletal survey.  X-rays can identify if bone cancer is present.  A bone scan requires that you receive a small harmless injection of a radioactive substance several hours before your test.  The substance collects in your bones in areas where the bone is breaking down or repairing itself.  A bone scan shows the extent of bone cancer.  A skeletal survey is a form of X-ray.  A skeletal survey is an assessment of the entire skeleton that shows rapidly growing cancer cells.  Your doctor may order other types of imaging tests as necessary.

A biopsy is used to confirm the diagnosis of primary bone cancer and rule out other conditions.  A biopsy can identify primary bone cancer and metastasized bone cancer.  The biopsy method that your doctor chooses depends on several factors, including the suspected type and location of the bone cancer.

If you have primary bone cancer, your doctor will assign your cancer a classification stage based on the results of all of your tests.  Staging describes the cancer and if it has metastasized. Primary bone cancer can spread to the lungs, lymph nodes, liver, distant organs, and other sites on the bone.  Staging is helpful for treatment planning and recovery prediction.

There is more than one type of staging system for cancer, and you should make sure that you and your doctor are referring to the same one.  Generally, lower numbers in a classification system indicate a less serious cancer, and higher numbers indicate a more serious cancer.  The stages may be subdivided into grades or classifications that use letters and numbers.

Treatment

Surgery for primary bone cancer usually includes a biopsy and surgical procedure.  Over half of people with primary bone cancer can have surgical treatment with limb salvage (limb-sparing) surgery.  This involves surgery to remove the cancer and replace the bone with a graft or endoprosthesis, an internal prosthesis.  However, amputation may be the only options for some people.  Limb salvage and amputation surgery is usually followed by rehabilitation.  Chemotherapy may be used for primary bone cancer that has spread, but it is seldom used as a treatment for primary bone cancer.  Radiation treatments may also be offered for relief of bony pain.
 

The experience of primary bone cancer, surgery, amputation, and cancer treatments can be an emotional experience for people with cancer and their loved ones.  It is important that you receive support from a positive source.  Some people find comfort in their family, friends, co-workers, counselors, and faith.  Cancer support groups are another good option.  They can be a source of information and support from people who understand what you are experiencing.  Ask your doctor for cancer support groups in your area.

Prevention

The exact cause of primary bone cancer is unknown.  There is no known way to prevent primary bone cancer at this time.  There is no routine screening test for primary bone cancer.  The best strategy is to have signs and symptoms evaluated promptly by your doctor.

Am I at Risk

Risk factors may increase your likelihood of developing primary bone cancer, although most people that experience this cancer do not have any risk factors.  You should tell your doctor about your risk factors and discuss your concerns.

Risk factors for primary bone cancer:

_____ Some bone cancers, especially osteosarcomas, appear to be hereditary.  If your close family members had an inherited form of bone cancer, your risk of developing bone cancer is increased.
_____ People with Li-Fraumeni syndrome or Rothmund-Thompson syndrome, inherited cancer syndromes, are more likely to develop osteosarcoma.
_____ Children with retinoblastoma, a rare inherited eye cancer, have an increased risk for developing osteosarcoma.
_____ People with Paget's disease have an increased risk of developing bone cancer.
_____ Multiple exostoses, also called multiple osteochondromas, is an inherited condition that causes bumps on the bones.  People with this condition have an increased risk for developing bone cancer.
_____ Large exposures of radiation increases the risk of bone cancer.  People that have received radiation as a treatment for other forms of cancer may have an increased risk of bone cancer.
_____ Bone marrow stem cell transplantation may increase the risk for bone cancer.

Complications

strong>Primary bone cancer most frequently spreads to the lungs and other areas of bone.  It can also metastasize to the lymph nodes, liver, and other distant organs.  Metastasized cancer also requires treatment.  Significant bone cancers can result in arm or leg amputation.  Primary bone cancer can return following treatment.  It most frequently returns first in the bones and lungs.  Primary bone cancer can be fatal.

Advancements

Researchers are gaining an understanding of how certain changes in DNA cause primary bone cancers to develop.  DNA is the genetic blue print for your cells.  Researchers hope this information will lead to a treatment.

Researchers are investigating new treatments for primary bone cancers.  Researchers are testing the usefulness of administering chemotherapy before surgery and directly into the artery that supplies an infected arm or leg.  Immunotherapy is another area of study.  Immunotherapy uses treatments to boost the immune system to help it fight cancer.  Additionally, researchers are studying methods to block the action of proteins that help cancer cells grow.