Immune System and Cancer

What is the Immune System and How Does it Work with Cancer?

The immune system is a natural part of our body. Its role is to get rid of foreign or damaged material and cells before they cause trouble. 

Most of the time, our immune system can find foreign invaders like bacteria and viruses, and destroy them. The immune system uses signals to attack them while leaving healthy cells alone.

Cancer is different from an illness caused by a bacteria or virus. It involves the uncontrolled growth of normal body cells. In other words, cancer cells may not be found by the immune system. Though they look different under the microscope, cancer cells can hide and grow. One way cancer cells hide is to express proteins on their surface to turn-on a "checkpoint" to stop an immune system attack.

The National Cancer Institute (NCI) studied common tumors in its Cancer Genome Atlas project. The research showed that bladder cancer, skin cancer and lung cancer have the most cellular changes (mutations). These types of cancer may be more likely to respond to treatments that help the immune system find cancer cells, called "immunotherapies".

What is Immunotherapy?

Immunotherapy is any treatment that makes the immune system stronger. For cancer, it helps the body find and attack cancer cells. The field of immuno-oncology studies how the immune system interacts with cancer. It uses that information to make new treatments.

Treatments like chemotherapy and radiation work differently. They try to kill growing cancer cells directly. Immunotherapies, on the other hand, block the signals (or "checkpoints"), and rev-up immune cells to attack or control cancer. These therapies make changes to our immune system in order to attack cancer.

What Happens Under Normal Conditions?

Your immune system is a network of cells, tissues and organs. They work together to recognize and kill invaders in your body.
The immune system protects us because it can tell the difference between self and non-self. "Self" means our own body tissues. "Non-self" means any odd cell or invader, like bacteria, viruses, parasites and fungus. Normally, our immune system will not attack a cell that it sees as "self".

What Happens When Cancer Cells Grow and Hide?

Cancer cells are tricky for the immune system. They come from our own cells. As they grow and spread, cancer cells change or mutate to look less and less like normal cells. Sometimes our immune system can sense these changes and react. Other times, the cancer cells can hide so they can grow.

Three things help cancers hide from the immune system:

  1. Antigenicity: An antigen is a special type of protein that is recognized by the immune system. Cancer cells may not have the right type or number of antigens to be recognized.
  2. Immunogenicity: Some cancer cells use signals to stop the immune system from an attack.
  3. The patient themselves: Some patients' immune systems react better than others to control cancer.

Key Statistics

  • 79,030 people in the U.S. will be diagnosed with bladder cancer this year. 
  • 50% or more patients with non-muscle invasive bladder cancer (NMIBC) can get advanced disease. Immunotherapy could be helpful. 
  • More than 50% of advanced or metastatic bladder cancer patients can't take standard chemotherapy, or chemo doesn't work for their cancer. Immunotherapy or a clinical trial in immunotherapy may be the best choice.
  • 90% of eligible patients don't know about or aren't considered for clinical trials. These patients may be helped from an immunotherapy trial. 

Hundreds of new immunotherapy treatments are being tested for cancer. While a small percentage of people have had success with new treatments so far, this research offers a great hope for the future.