What are the other Names for this Condition? (Also known as/Synonyms)

• Postradiation Osteogenic Sarcoma
• Post-Radiation Osteogenic Sarcoma
• Radiation-Related Osteosarcoma

What is Post-Radiation Osteosarcoma? (Definition/Background Information)

• Osteosarcoma forms a class of highly-cancerous, high-mortality, bone tumor. After multiple myeloma, it is the second-most common primary tumor of the bones

• Post-Radiation Osteosarcoma is a type of secondary osteosarcoma. For a diagnosis of this tumor type, two criteria must be met:

  • There must be a history of radiation at the site of tumor

  • There should be an interval period, between the times when radiation is given, to the development of osteosarcoma. This time period is called the latent period and the average latent period is approximately 16 years       

• The two most common locations involved in Post-Radiation Osteosarcoma are the shoulder area and pelvic bones, because radiation to these areas are given for breast cancer and pelvic cancer respectively
• The exact cause of the condition is unknown and presently, it is not possible to prevent Post-Radiation Osteosarcoma occurrence
• A treatment of this bone tumor may involve surgery, chemotherapy, and radiation therapy. The prognosis of Post-Radiation Osteosarcoma depends on the stage of cancer; higher grade osteosarcomas indicate a poorer prognosis

Based on where they occur, Osteosarcoma is classified as Medullary Osteosarcoma (occurring in the bone cavity) and Surface Osteosarcoma (occurring on the bone surface).

• Medullary Osteosarcomas are of several different types, and these include:
  • Conventional Osteosarcoma
  • Osteosarcoma of Jaw Bones
  • Post-Radiation Sarcoma
  • Osteosarcoma arising in Paget's Disease of Bone
  • Osteosarcoma in other Benign Conditions           
  • Telangiectatic Osteosarcoma
  • Small Cell Osteosarcoma
  • Low-Grade Osteosarcoma
  • Multicentric Osteosarcoma
• Surface Osteosarcomas are of several different types, and these include:
  • Parosteal Osteosarcoma
  • Periosteal Osteosarcoma
  • High-Grade Surface Osteosarcoma       

Who gets Post-Radiation Osteosarcoma? (Age and Sex Distribution)

• Post-Radiation Osteosarcoma (or Radiation-Related Osteosarcoma) affects those who have been subject to radiation therapy earlier
• The age group affected by this condition is mostly patients, who are in their 6th decade of life (age 50-59 years)
• There is no known ethnic/racial preference; the condition is known to occur worldwide

What are the Risk Factors for Post-Radiation Osteosarcoma? (Predisposing Factors)

The risk of Post-Radiation Osteosarcoma is linked to the following factors:

• A previously performed radiotherapy for other cancer conditions - the tumor may be radiation-induced. The radiation has an expected side effect of damaging the genetic material in the normal cells. This can lead to the development of a “secondary” cancer
• Genetic mutations that are associated with osteosarcoma

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Post-Radiation Osteosarcoma? (Etiology)

• The exact cause and mechanism of Post-Radiation Osteosarcoma formation is unknown
• The tumor is thought to occur due to preexisting radiation-exposure
• Radiation-influenced tumor takes many years to develop, after the radiation exposure has ceased. This radiation may have been previously administered for treating any other tumor

Radiation therapy: Radiation therapy involves using x-rays (or other radiation) to kill cancerous cells. High-powered radiation beams are directed to particular body regions to target cancer. In the process, healthy cells can also be damaged.

What are the Signs and Symptoms of Post-Radiation Osteosarcoma?

The presentations are based on the location of the tumor. Post-Radiation Osteosarcoma signs and symptoms include:

• In the initial growing phase of the tumors, they are normally asymptomatic. The soft tissue tumors grow at a moderate rate, and then they suddenly start to rapidly progress
• Due to large size of the tumor, the adjoining organs, nerves, and muscles may be compressed or restricted. Often, these signs along with pain and tenderness, are the first indications of Post-Radiation Osteosarcoma
• In some individuals, organ dysfunction and internal hemorrhages may be observed. These may be sudden and spontaneous developments
• Lesions beneath the skin (in rare cases), may appear as painful inflammations

How is Post-Radiation Osteosarcoma Diagnosed?

A diagnosis of Post Radiation Osteosarcoma is made using the following tools:

• Physical examination, evaluation of patient’s medical history involving pervious exposure of radiation
• Histopathological studies conducted on a biopsy specimen - the specimen is examined under a microscope by a pathologist, to arrive at a definitive diagnosis
• X-ray studies of the tumor
• MRI scan or CT scan of the affected region

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Post-Radiation Osteosarcoma?

Complications of Post-Radiation Osteosarcoma are dependent on the site and severity of the tumor. These include:

• Damage of the following organs due to metastasis - liver, bones, and lungs
• Usually by the time osteosarcomas are detected, chances are that they would have proliferated and metastasized aggressively, damaging organs and tissues beyond repair
• They are known to have a high recurrence rate, even on surgical excision and removal
• Deep-seated tumors (those buried inside the body tissues) may cause damage to adjoining tissues and organs
• Blood loss during invasive treatment methods may be heavy
• Damage to vital nerves, blood vessels, and surrounding structures, during surgery
• Side effects from chemotherapy (such as toxicity), radiation therapy

How is Post-Radiation Osteosarcoma Treated?

Treatment measures for Post-Radiation Osteosarcoma include the following:

• Any combination of chemotherapy, radiation therapy, and invasive procedures maybe used to treat the tumor
• Wide surgical excision of osteosarcoma and removal of the entire lesion is the standard treatment mode. If the tumor is not fully removed, then it will recur
• Embolization of the tumor is used to provide temporary relief from the symptoms, and reduce blood loss during a surgical procedure
• When the tumor is at an inaccessible location, or is unsafe for surgical intervention, non-invasive procedures are adopted
• Post-operative care is important: A minimum activity level is to be ensured, until the surgical wound heals
• Follow-up care with regular screening and check-ups are important

How can Post-Radiation Osteosarcoma be Prevented?

• Current medical research have not established a way of preventing Post-Radiation Osteosarcoma occurrence
• However, the presence of any tumor or lesion should be immediately informed to the physician and periodic follow-up and screening maintained
• Regular medical screening at periodic intervals with blood tests, scans, and physical examinations, are mandatory for those who have already endured the tumor. This is due to both its high metastasizing potential and chances of recurrence. Often several years of active vigilance is necessary

What is the Prognosis of Post-Radiation Osteosarcoma? (Outcomes/Resolutions)

• The prognosis of Post-Radiation Osteosarcoma is worse, when compared to conventional osteosarcoma

Several prognostic markers are identified by research which helps determine the prognosis of Post-Radiation Osteosarcoma. Many of these prognostic markers are based upon defective genes or defective proteins found in the tumor. Some of these genetic defects that alter the prognosis are explained below.

The following conditions result in or indicate a poor prognosis:

• 13q14 loss of heterozygosity (gene loss) and mutations in Rb gene
• Presence of MDR-1 gene mutation, which is a multi-drug resistant gene, results in tumor not responding to certain chemotherapy agents
• The presence of c-FAS mutations in patients result in poorer prognosis, due to a poor response of the condition to chemotherapy and a higher chances of recurrent and metastatic osteosarcoma
• HER-2 over expression in tumor
• Loss of M-TAP gene

Other factors that are related to osteosarcoma prognosis include:

• Loss of heterozygosity of 18q in patients with Paget’s disease of the bone, has been shown to increase the development of osteosarcoma, in such patients
• Studies have shown that such tumors in children have the worst prognosis, compared to young adults with the tumor
• Some studies seem to indicate that men with these bone tumors have poorer prognosis, than women; but, this has not been substantiated
• Location of the tumor also determines its outcome; tumor in distal parts of the knee and elbow, have better outcomes, than those at other locations
• The size of the tumor also determines its prognosis; normally, larger tumors have much poorer prognosis than smaller-sized tumors
• Duration of symptoms are important factors too:
  • A shorter duration of symptoms lead to a worse prognosis
  • A longer duration of symptoms lead to a better prognosis          
• A presence of spontaneous necrosis leads to the worst prognosis. Spontaneous necrosis means a type of necrosis that is present due to tumor growth and not due to treatment with chemotherapy

Additional and Relevant Useful Information for Post-Radiation Osteosarcoma:

There are approximately 1000 cases of osteosarcomas, diagnosed each year in the United States.