Osteosarcoma (Most often found in pediatric patients)

Osteosarcoma, also called osteogenic sarcoma, is a rare bone cancer but is the most common type in children, teens and young adults. Each year, about 1,000 new cases are diagnosed in the United States and about half of these are in children and adolescents. About two to three percent of childhood cancers are osteosarcomas, but they make up a much smaller percentage of adult cancers. The cancer cells in these tumors look like early forms of bone cells that normally help make new bone tissue, but the bone tissue in an osteosarcoma isn’t as strong as that in normal bones. 

Osteosarcoma most commonly occurs in the bones around the knee, but other sites include the thighbone, lower leg, upper arm bone, pelvis, shoulder and skull. It may grow into nearby tissues, such as tendons or muscles.  

Types & Stages 

There are three main types of primary osteosarcoma and they differ based on the bone cancer's location and appearance. These include:  

• Intramedullary osteosarcoma. This type is the most common and accounts for nearly 80 percent of all osteosarcoma diagnoses. These bone cancers develop in the medullary cavity of a long bone, such as the femur. Additionally, there are a number of subtypes of intramedullary osteosarcoma, each based on the type of cells that make up the tumor. Common subtypes include osteoblastic, condroblastic, fibroblastic, small-cell and epithelioid.
   
• Juxtacortical osteosarcoma. This type is the second most common and accounts for between 10 and 15 percent of all diagnoses. These bone cancers develop on the outer surface of the bones or the periosteum (the dense layer of connective tissue that covers the bones).
   
• Extraskeletal osteosarcoma. This type is extremely rare, accounting for fewer than five percent of all diagnoses. These tumors arise in soft tissues and are not attached to bone;  often at a site of prior radiation therapy.

With any of these types of osteosarcoma, oncologists may also use the terms “synchronous” and “metachronous” to refer to osteosarcomas that involve more than one lesion in more than one bone. With synchronous osteosarcomas, these lesions are detected within a six-month span; with metachronous osteosarcomas, the lesions are discovered more than six months apart.

Signs & Symptoms 

Osteosarcoma signs and symptoms most often start in a bone. The cancer most often affects the long bones of the legs, and sometimes the arms. The most common symptoms include:

• Bone or joint pain that might come and go at first and can be mistaken for growing pains
• Pain related to a bone that breaks for no clear reason
• Swelling near a bone

Diagnosis 

Tests and procedures to diagnose osteosarcoma include:              

• Imaging tests. These may include:
   
  • X-rays. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
     
  • Computerized tomography scan (CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body.  
     
  • Magnetic resonance imaging (MRI). A diagnostic procedure that uses a [combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
     
  • Bone scans. A whole-body bone scan is a nuclear medicine test to check your bones for issues or changes. You receive an injection of a substance called a radiotracer. The radiotracer collects in areas of irregular activity and highlights these areas on an imaging scan.  
     
  • Positron emission tomography scan (PET scan). An imaging test that uses a radioactive drug called a tracer—most often injected into a vein in your hand or arm—to show both typical and atypical metabolic activity. The PET images are typically combined with CT or MRI and are called PET-CT or PET-MRI scans.  
     
• Biopsy. A biopsy is needed to confirm a osteosarcoma diagnosis. A procedure to remove some cells for testing. The sample might be removed with a needle put through the skin. Or the sample might be taken during surgery to remove the cancer. The type of biopsy depends on the cancer's location.

Treatment 

Osteosarcoma treatment most often includes:

• Surgery. The goal of surgery is to remove all the cancer cells. In planning the surgery, the healthcare team keeps in mind how the surgery will affect your or your child's daily life. The extent of surgery for osteosarcoma depends on several factors, such as the size of the cancer and where it is. Operations used to treat osteosarcoma include:
   
  • Surgery to remove the cancer only, also called limb-sparing surgery. Most osteosarcoma operations can be done in a way that removes all the cancer and spares the arm or leg. Whether this type of surgery is an option depends, in part, on the extent of the cancer and how much muscle and tissue need to be removed. If a section of bone is removed, the surgeon will rebuild the bone. How the bone is rebuilt depends on the situation. Options include metal implants or bone grafts.
     
  • Surgery to remove the affected arm or leg, also called amputation. Rarely a surgeon might remove the affected leg or arm to get all the cancer. After surgery, an artificial arm or leg can be used. This is called a prosthesis.
     
  • Surgery to remove the lower portion of the leg, also called rotationplasty. Rotationplasty might be an option for osteosarcoma in and around the knee joint. In this surgery, the surgeon removes the cancer and surrounding area, including the knee joint. The foot and ankle are then rotated and put backward on the part of the leg that remains above the knee. The ankle then works as a knee. A prosthesis is used for the lower leg and foot. This surgery is sometimes a good option for children who are still growing. It allows them to take part in sports and physical activities.
     
• Chemotherapy. For osteosarcoma, chemotherapy is often used before surgery. It can shrink the cancer and make it easier to remove. After surgery, chemotherapy treatments might be used to kill any cancer cells that might remain. For osteosarcoma that returns after surgery or spreads to other areas of the body, chemotherapy might help relieve pain and slow the growth of the cancer.
   
• Radiation therapy. Radiation therapy treats cancer with powerful energy beams. The energy can come from X-rays, protons or other sources. During radiation therapy, a patient will lie on a table while a machine moves around their body. The machine directs radiation to precise points on their body. Radiation isn’t often used to treat osteosarcoma, but might be suggested instead of surgery if the latter can't remove all the cancer.

Causes & Risk Factors 

Most people with osteosarcoma don't have any known risk factors for the cancer. But these factors can increase the risk of osteosarcoma:

• Hereditary disorders. Certain conditions that run in families, including:  
   
  • Li-Fraumeni syndrome, a predisposition to multiple types of cancers (such as soft tissue sarcomas, breast cancer, brain tumors, osteosarcoma and others) caused by a mutation in the p53 tumor-suppressor gene that normally curbs cancer.
     
  • Rothmund-Thompson syndrome, a syndrome that includes skeletal problems, rashes, short stature and an increased risk of developing osteosarcoma caused by an abnormality in the REQL4 gene.
     
  • Hereditary retinoblastoma, a cancer of the eye that usually happens in children younger than four years old.
     
• Other bone conditions. These include Paget's disease of bone and fibrous dysplasia.
   
• Prior treatment. With radiation therapy or chemotherapy.

Screening 

There is no routine screening test for osteosarcoma.