Cancer means an uncontrolled growth of cells in the body. The term bone cancer is used for any cancer that starts in the bones. This is also called primary cancer of the bones. Cancers that begin in one part of the body and spread to bones (metastasis) are not categorized as bone cancer. These cancers are called secondaries or secondary cancer affecting the bones. Only around 0.2-0.5% of the cancers affecting the bones are primary bone cancers. In children, however, bone cancers account for around 5% of all cancers. According to the American Cancer Society, around 3,160 Americans will be diagnosed with bone cancer in 2021. The estimates also suggest that bone cancer may cause around 2060 deaths in the United States in 2021.
Bone cancer is of various types. The three main types of bone cancer are:
- Osteosarcoma: It is the commonest type of bone cancer. Around 3% of cancers seen in children are osteosarcomas. This cancer arises from the bone-forming cells called osteoblasts. Hence, it is seen more commonly in age-groups where growth spurt occurs, such as teens.
- Chondrosarcoma: It is the second most common primary bone cancer. It arises from the cartilage forming cells.
- Ewing sarcoma: This tumor may arise in immature nerve tissues in the bone marrow. Ewing sarcoma generally affects the long bones, such as the thighbone (femur), upper arm bone (humerus), and shinbone (tibia), although it may affect the bones of the pelvis as well. When this cancer starts in the muscles and soft tissues, it is called extraosseous Ewing sarcoma.
What are the warning signs of bone cancer?
The warning signs of bone cancer generally include:
- Bone pains
- Swelling in the affected area
- Fractures that may occur with minor injury or in the absence of any injury
- Unintended weight loss
How do you detect bone cancer?
Doctors diagnose bone cancer by:
- Medical history: This includes asking for the patient’s symptoms, when and how the symptoms started to show, and the patient’s history of any medications or underlying health conditions. The physician may also enquire about any history of cancer in the patient or their relatives (parents, children, or siblings).
- Physical examination: The physician conducts a detailed examination of the affected site and the rest of the body to identify any signs of cancer spreading (metastasis) or underlying health conditions.
- Imaging studies: X-ray is generally done as an initial imaging study to look for any bone abnormality. Other imaging studies, such as computed tomography (CT), magnetic resonance imaging (MRI), radionuclide bone, and positron emission tomography (PET) scans, may be done. The results of imaging studies should indicate the site of the primary tumor, metastasis, and the type of tumor to the doctor.
- Biopsy: This test involves taking a piece of tissue from the tumor and examining it in the laboratory under a microscope. Biopsy reveals whether the mass is because of cancer or other diseases. It also informs about the type of cancer.
- Blood tests: The physician orders certain blood tests to check for various parameters, such as blood counts, blood sugar, biomarkers (certain substances whose blood levels may be raised in case of a tumor), and electrolytes (such as calcium, magnesium, and sodium).