Introduction to Cancer Immunotherapy


IMMUNOTHERAPY IS ONE OF THE MOST RECENT ADVANCES IN CANCER THERAPY

Radiation, chemotherapy, and surgery are the traditional tools in the fight against cancer. Radiation was discovered in the 1800's by Marie Curie. Chemotherapy evolved from mustard gas (World War 1), and surgery dates back to the ancient Egyptians.

These treatment modalities are all based on destroying cancer cells by burning them (irradiation), poisoning them (chemotherapy) or removing them (surgery). While they can effectively kill or remove cancer cells, the use of these treatments often is limited because large numbers of healthy cells also tend to be destroyed. This often results in extreme morbidity and/or disfigurement of the patients treated with them. In the worst cases, these treatments can sometimes result in the patient's death.

To date, there is no "magic bullet" in the treatment of cancer, and because of the complexity of cancer biology, it will likely not be attainable. It is now generally agreed that the future of cancer therapy lies in the combination of therapies with different mechanisms of action.

Immunotherapy is one of the more recent approaches to cancer therapy. It is based on the generally-accepted hypothesis that the immune system is the best tool humans have for fighting disease.

Immunotherapies have the potential to be used to fight cancer by either applying an external stimulus to the immune system to make it act more 'forcefully' or 'smarter', or by providing the immune system with man-made or naturally-derived tumor specific proteins made outside of the body so that the immune system can recognize the tumor as a foreign entity and destroy it.

Immunotherapy is sometimes used by itself to treat cancer, but it is most often used in combination with traditional treatments like radiation, chemotherapy, and surgery in order to enhance their effects. One of the possible benefits of immunotherapy is that it has the potential not to be as toxic as radiation, chemotherapy, and surgery.  In addition, immunotherapy often may offer a different mode of attack on the tumor, thereby affording both patients and doctors alike a potential new treatment in the fight against cancer.

   

LIMITATION OF THE IMMUNE SYSTEM IN FIGHTING CANCER
AND THE NEED TO EMPOWER THE IMMUNE SYSTEM

In the case of cancer, the immune system alone often fails to effectively fight the tumor for the following reasons:

  • The normal immune system is 'blind' to tumor cells because the tumor cells are derived from the body's own cells. The body 'thinks' of the tumor as 'self', which creates a phenomenon known as 'tumor tolerance'.
  • The immune system may recognize certain cancer cells, but the response may not be strong enough by itself to destroy the cancer (because the response is insufficient in amount, it does not occur in the right place in the body, or it does not send the right 'immune cells').
  • The tumor has the ability to defend itself. Cancer cells may secrete substances that keep the immune system in check.

In the case of cancer, the immune system thus may need a boost to potentially be able to become more effective in fighting the cancer.