DEAR DR. ROACH: I have read about using the immune system’s response as a mechanism to battle cancer (such as brain and pancreatic) and to reduce the devastating impact that cancer and its treatment has on humans. I understand current drug trials show promising results. How do doctors and scientists use the immune system to treat cancer?

• J.W.

ANSWER: The concept of using the immune system to treat cancer is old, but the ability to do so has dramatically improved in the past few years. There are a few specific types of treatments that I’d like to highlight:

Immune checkpoint inhibitors are treatments that release inhibitions on the immune system. (These “strengthen” the immune system, which has beneficial but also potentially toxic effects.) For melanoma, the most dangerous form of skin cancer, these treatments have revolutionized treatment and led to dramatically improved outcomes in people whose melanoma has spread. Response rates are up to 60% in a disease where the prognosis used to be dismal.

The unleashed immune system can destroy cancer very effectively, but it also can attack healthy organs, with many people (between 10% to 60% depending on drugs and doses) developing damage to the skin, lungs, liver, thyroid, colon and heart. These toxicities range from mild to life-threatening.

The body’s own immune cells can be genetically engineered to kill cancer cells. Chimeric antigen receptor T cells (CAR T cells) can be specifically changed to recognize cancer cells.

This can lead to complete remission with some cancers, especially some leukemias and lymphomas. Unfortunately, they can also attack the body, leading to neurological damage that can be very serious.

Developing cancer vaccines is a highly promising strategy for personalizing the immune system to attack a person’s own cancer. Although the United States has recently made dramatic cuts to its support of this research, researchers in other countries continue to study this.

It can be used in combination with other traditional or immune-based treatments.

The immune system can be used to help treat cancer effectively, but there is still the potential for serious side effects.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.

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