Immunotherapy vs Chemotherapy: Understanding the Key Differences

More people may know of chemotherapy, or chemo, as a cancer treatment. But immunotherapy is gaining traction, and for good reason. Immunotherapy is a promising advancement in the treatment of many cancers, including advanced endometrial cancer. It has even become the first line of treatment for some cancers.¹

So, when it comes to immunotherapy versus chemotherapy, how do the two differ? And what is right for you?

How do immunotherapy and chemotherapy work?

Both immunotherapy and chemotherapy target tumor cells, but they use different methods. Immunotherapy works with your body's defenses, acting on your immune system. Chemo works directly on the cancer cells growing inside you.

Cancer immunotherapies work in several different ways to alert and train a person's immune system to identify and destroy malignant cells. The therapies do this by triggering a stronger-than-normal immune response.¹

Basically, immunotherapy trains your body's defenses to recognize cancer cells, then turns the immune system against the cancer. The idea of harnessing the human immune system to fight cancer dates back more than a century.³

Ideally, immunotherapy produces immune cells that can seek out and eliminate malignant cells.⁴

Chemotherapy works differently. It's a drug that directly attacks fast-growing tumor cells by targeting all rapidly dividing cells inside your body. But healthy cells sometimes get destroyed in the process, too.¹

How do I know which is better?

There are pros and cons to each treatment. What's right for one person may not be right for another. Key differences between immunotherapy and chemotherapy include:^1,2

• Treatment time – Treatment length for each therapy depends on many different factors, and treatment will be unique to you and your cancer. On top of that, immunotherapy may continue working even after the treatment period has ended. Chemo, on the other hand, only destroys cancer cells while the drugs are in your body.
• Side effects – Immunotherapy can result in an overstimulated immune system. Side effects range from mild, such as skin rashes and diarrhea, to severe. Chemo sometimes destroys healthy cells that divide rapidly. For example, it may destroy cells in your hair follicles, causing you to lose hair. Or it may damage cells in your gut lining, causing nausea.
• Length of time to noticeable results – The effects of immunotherapy may take longer to notice than the effects of chemotherapy. Chemo can shrink tumors quickly. But in the early stages of immunotherapy, tumors may appear to first grow before they shrink. This apparent growth is likely due to immune cells penetrating the tumor, which can make it look larger.

Can I use both?

Traditional cancer treatments include various combinations of immunotherapy, chemotherapy, and surgery. Treatment often depends on the type of cancer you have and where it's located.

But the lines between immunotherapy and chemotherapy are blurring. For example, some of the newer immunotherapies include built-in anti-cancer drugs. Known as antibody-drug conjugates, they send antibodies carrying chemotherapy drugs directly to the malignant cells. Delivering the toxic drugs straight to the cancer cells can lessen some of the worst side effects of traditional chemo.⁵

Ask your doctor what treatment is best for you. Keep in mind that your treatment will be tailored to your cancer. Tell us about your experience in the comments below, or share your story with the community.