Other Names

Bone cancer, Cancer of the bone, Tumor - Bone

Overview

Bone tumors present with many different symptoms. They range in their biological potential, from the harmless to the rapidly fatal. The varying degrees of outcomes make it essential to accurately diagnose and treat these tumors. In many cases, if bone cancer is properly diagnosed and treated patients can maintain full function of the affected bone.

Fortunately, most tumors are benign and pose no long term health issues. Benign tumors vastly outnumber their malignant counterparts. Benign tumors are most frequently seen within the first three decades of life. However, bone tumors that appear later in life have a higher tendency to be malignant.

Causes, Incidence and Risk Factors

The cause of most bone tumors is unknown. Genetic alterations, similar to those that occur in other tumors, have a role to play. Secondary deposition of malignant cells, from other tumors elsewhere, account for only a small fraction of bone tumors.

In the US, about 2100 new cases of malignant bone tumors are diagnosed annually. These newly diagnosed patients come from all age groups and the tumors can arise from virtually any bone in the body. However, the origin of most tumors is generally the long bones of the arms and legs, more specifically the humerus (upper arm bone) and femur (upper leg bone). Specific types of tumors target certain age groups and anatomical sites.

Risk factors:

• Bone infarcts
• Chronic osteomyelitis
• Paget's disease
• Radiation
• Metal prosthesis

Signs and Symptoms

Clinically, bone tumors manifest themselves in various ways. The more common benign lesions have no symptoms and are detected as an incidental finding. If you notice the following symptoms, seek immediate medical attention for evaluation:

• Tender and warm feeling over a swollen area
• Slow-growing mass with stretched, shiny, smooth skin
• Nagging pain, night pain
• Limitation of movement
• Fever
• Loss of weight and loss of appetite

Sometimes, the first hint of the presence of a tumor is a pathological fracture of the affected bone. For example, if a patient breaks a bone after a mild injury, such as bumping into a door, this could signal a weakness in the bone caused by a tumor.

Screening and Diagnosis

After a thorough clinical examination, X-ray is the first investigation done to confirm the presence of a tumor. X-rays reveal the exact location, extent and the possible type of a tumor. Different bone tumors vary in their characteristic appearance on an X-ray.

Other tests are done to confirm the presence of tumor, determine its histological grade and it's presenting stage. These are prognostic factors in the treatment of bone cancer. Such tests include:

Tests:

• Serum enzymes like alkaline phosphatase - generally elevated. It is a useful parameter to follow up the regression of a tumor after treatment. A rise in this enzyme, after an initial fall, due to tumor removal suggests recurrence of the tumor or metastasis.
  
  
• Biopsy: Open biopsy, Core biopsy or fine needle aspiration cytology (FNAC) may be done. A small amount of tissue is taken and examined under a microscope to confirm the presence of the tumor.
  
  
• Chest X-ray to rule out the spread of the tumor
  
  
• CT and MRI scans to evaluate the extent of local spread and distant metastasis

Treatment

Wherever possible, excision of the tumor is the best mode of treatment. For sites like the spine where excision is sometimes not technically possible radiotherapy is given.

The following treatment methods are commonly used:

• Excision: Excision is feasible where a tumor affects a bone whose removal does not hamper normal functioning. Extensive spread of a tumor may require amputation.
  
  
• Excision with reconstruction: If the tumor has affected a patients ability to function, the bone tumor is removed (excision) and the defect is repaired up by reconstructing the bone through methods like arthrodesis or arthroplasty.
  
  
• Curettage: Curettage involves scraping out the malignant bone cells. It has a high recurrence rate but deformity is minimal. Additional techniques like cryotherapy used in conjunction with curettage often have a better result. The thermal effect of bone cement can also be used to kill residual malignant tumor cells.
  
  
• Radiotherapy: Radiotherapy is preferred for tumors that are inaccessible to surgical treatment like the spine or for those who do not prefer surgery.
  
  
• Chemotherapy: Preoperative & postoperative chemotherapy, has a good prognosis for patients with highly malignant tumors like osteosarcoma. Drugs used are Methotrexate, Citrovaorum factor, Endoxan and Cisplatinum.
  
  
• Immunotherapy: This is a new concept. It is not yet popular or widely practiced. This technique involves using immune cells from a tumor survivor to combat tumor cells in a newly diagnosed patient.

Recovery

Most bone tumors are benign and pose no serious health treat. However, any sign of cancerous bone or bone deformity should be evaluated by a trained physician. Without treatment, malignant tumors progress rapidly and are fatal. In the past decade, however, with the above modalities of treatment, tumor survival rates have climbed steadily. With newer drugs and newer approaches to treatment, the possibility of a 5-year disease-free period is as high as 70%. Additionally, it is necessary to have a regular follow up, to identify recurrences and micro metastasis as early as possible and prevent further growth.

References

1. Robbins and Cotran, Pathologic basis of disease 7th edition, Chapter 26, Bone tumors and Tumor like lesions, Pages 1292-1303
   
   
2. Essential Orthopedics by J. Maheshwari. 3rd edition. Chapter 30, Bone tumors. Pages 214-227.