Biological therapy is a form of treatment that uses the body’s immune system to fight cancer. The therapy can work either directly or indirectly to enhance, repair or stimulate the immune system’s response to cancer.  Certain types of biological therapy also may be used to reduce the side effects of cancer treatments such as chemotherapy.

Biological therapy differs from chemotherapy in that chemotherapy drugs directly attack cancer cells, while biological therapy drugs (also called biological response modifiers) help the body’s immune system to fight cancer.

Some drugs, such as interferons, work with the immune system and act directly on the cancer cells as well. Other drugs, such as colony-stimulating factors (CSF) do not work directly on cancer cells. Instead, these agents work to increase blood cell production impaired by cancer or cancer therapy. 

Experts are unsure exactly how biological therapy works, but speculate that it may:

• Stop or slow cancer cell growth
• Help the immune system recognize and destroy cancer cells
• Prevent cancer from spreading throughout the body

In some cases, biological therapy may be the only treatment used to fight a patient’s cancer. In other cases, it may be used in combination with other treatment such as surgery, chemotherapy or radiation therapy. 

Biological therapy is most often used in clinical trials, and has been used to treat a number of cancers, including:

• Melanoma
• Cancers of the blood (leukemias)
• Breast, ovarian and colon cancer
• Kaposi’s sarcoma
  
• Lung cancer
  
• Pancreatic cancer
  
• Colorectal cancer
  
• Kidney cancer
• 

While biological therapy has shown great benefits in treating some cancers, like most treatments, it may cause side effects. These can include a rash or swelling at the injection site, flu-like symptoms and fatigue. The side effects are usually related to increased stimulation of the immune system and vary according to the type of treatment. The most common side effects include flu-like symptoms (e.g. fever, chills, nausea), fatigue and loss of appetite. Biological therapy is relatively new and there is limited information about the long-term effects of the treatments.