Definition

Osteosarcoma is a type of bone cancer that originates from bone-forming cells called osteoblasts. It is the most common type of bone cancer and is highly malignant, meaning it can spread to other organs in the body.

There are an estimated 3.4 million new cases of osteosarcoma worldwide each year. Osteosarcoma is the third most common cancer in adolescents, with most cases occurring during the second decade of life.

Causes

Osteosarcoma typically appears suddenly. The disease is believed to be caused by mutations (genetic changes) in osteoblasts. These mutations cause osteoblasts to grow and multiply uncontrollably, forming tumors. The tumor then invades and damages the surrounding healthy tissue.

Risk Factor

As with other types of cancer, most cases of osteosarcoma occur sporadically, meaning the frequency is unpredictable and varies between individuals. The most common risk factors for osteosarcoma include:

Age and Gender

Osteosarcoma is most frequently found in children and adolescents, with teenagers being the most affected age group. The cancer tends to develop between the ages of 10 and 30, particularly during periods of rapid growth in adolescence. The risk decreases in middle age but can increase again after age 60. Osteosarcoma is more common in males than females, with a ratio of 3:2.

Height

People with osteosarcoma tend to be taller than their peers.

History of Radiation

Individuals who have undergone radiation therapy for other cancers are at a higher risk of developing osteosarcoma in areas that received radiation. The risk increases with younger age and higher doses of radiation.

Certain Bone Diseases

Paget’s disease (a disorder that disrupts the normal cycle of bone regeneration) can increase the risk of osteosarcoma. Bones affected by Paget's disease become thicker and harder but are more fragile than normal bones.

Genetic Conditions

Some genetic mutations can increase the risk of osteosarcoma, such as:

• Retinoblastoma, a type of eye cancer that occurs in children.
• Li-Fraumeni syndrome, a genetic disorder that significantly increases the risk of various cancers due to mutations in tumor suppressor genes.
• Werner syndrome, a rare disorder involving the WRN gene that affects DNA repair.
• Rothmund-Thomson syndrome is characterized by short stature, rashes, hair loss, and skeletal abnormalities.

Symptoms

Osteosarcoma typically affects adolescents under the age of 20, as their bones are still growing rapidly. The cancer most often develops in large bones with high growth rates, such as the thighbone and shinbone near the knee and the upper arm bone near the shoulder.

Common symptoms include:

• Bone pain, which worsens at night or after physical activity.
• Swelling, redness of the skin covering the bone, and warmth in the painful area.
• Sudden bone fractures without prior injury, often after normal activities.
• Limited movement due to pain and changes in bone shape.

Other symptoms that may occur as cancer spreads include:

• Fever
• Fatigue
• Unexplained weight loss
• Pale complexion
• Symptoms related to cancer affecting other organs.

In extremely rare cases, where the cancer is located at the base of the spine or pelvis, the patient may experience back pain. Loss of bowel or bladder control is also possible if the cancer is located in the pelvis or base of the spine.

Diagnosis

Diagnosis is made based on the patient’s medical history, symptoms, physical examination, and supporting tests. The following diagnostic tests are commonly used for osteosarcoma:

Blood Tests

Laboratory tests are performed to rule out other potential causes of pain and identify markers of tumors and inflammation.

X-ray (radiograph)

Imaging is conducted on bones with symptoms or signs of disease. Contrast-enhanced X-rays may be used, where a radioactive substance is injected into the bloodstream. Tumorous bones absorb the substance more rapidly than normal bones.

Other Imaging Techniques

A CT scan helps assess the extent of tumor invasion and spread to nearby organs. MRI provides a detailed view of the bone and surrounding tissues, while PET scans (positron emission tomography) show cancer spread throughout the body using radioactive material.

Biopsy

A biopsy involves taking a tissue or bone sample from the painful or swollen area for laboratory analysis to identify tumor cells causing osteosarcoma.

Management

Complications

Complications arise in patients whose osteosarcoma is diagnosed and treated late. The survival rate for this cancer is relatively low, around 20%, especially if the cancer has spread to other organs.

Advancements in chemotherapy and surgical techniques have improved the five-year survival rate to over 60%, depending on the type of cancer, the patient's response to treatment, and the extent of the cancer’s spread. When diagnosed early and treated before cancer spreads, the five-year survival rate for osteosarcoma across all age groups is approximately 77%.

Prevention

Osteosarcoma is sporadic, and there are no specific preventive measures for this cancer. Cancer, in general, has multifactorial causes, many of which are unknown.

Osteosarcoma is associated with genetic mutations in osteoblasts. If you have a family history of bone tumors or have undergone radiation therapy on your bones, you may be at increased risk. Maintaining a healthy lifestyle is recommended for those with risk factors.

When to See A Doctor?

The most common symptoms of osteosarcoma are bone pain and swelling at the affected site. If you experience these symptoms, it is advisable to consult a doctor for further evaluation.

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