Immunotherapy vs. Chemotherapy: What’s the Difference?

Immunotherapy has become an increasingly available and vital cancer treatment option in recent years. Many patients learning about immunotherapy want to know: how does immunotherapy compare to chemotherapy? What are the main differences between the two treatments? When should I choose immunotherapy vs. chemotherapy? To answer these pressing questions, we created a patient education video to explore the basic idea behind immunotherapy and discuss the differences between immunotherapy and cancer.

Although you should always speak to your health care professionals and seek their guidance about your treatment options, it’s also important for patients themselves to understand their treatments and how that could change their experiences and outcomes. Immunotherapy has the potential to help people affected by cancer—here’s why.

What is immunotherapy?

Cancer immunotherapy is a treatment that empowers a patient’s own immune system to fight cancer. Immunotherapy works to harness and enhance the natural powers of the immune system to work against the disease—by enabling it to recognize, target, and eliminate cancer cells throughout the body.

Immunotherapy can be given alone, or in combination with other types of cancer treatments. It has already proven to be an effective treatment for patients with various types of cancers, making it the most promising new cancer treatment approach since the first chemotherapies were developed in the 1940s.

What is chemotherapy?

Chemotherapy, often called "chemo," is a treatment with drugs that kill cancer cells directly. Chemotherapy attacks all rapidly-dividing cells within the body, effectively targeting fast-growing tumors. Chemotherapy can be used alone or in combination with surgery, radiation, or immunotherapy.

So what’s the difference?

Unlike chemotherapy, which acts directly on cancerous tumors, immunotherapy treats patients by acting on their immune system. Immunotherapy can boost the immune response in the body as well as teach the immune system how to identify and destroy cancer cells.

Immunotherapy vs. chemotherapy: Side effects

In order to destroy cancerous tumors, chemotherapy is intended to attack rapidly dividing cells within the body, which may include both cancerous and non-cancerous cells, such as hair follicles and the lining of the gut. These attacks on healthy cells may causes some of chemotherapy’s more well-known side effects, such as hair loss and nausea. In contrast, immunotherapy’s potential side effects usually result from an overstimulated or misdirected immune response, and can range from mild to moderate or severe and can become potentially life-threatening under certain circumstances.

Learn more about immunotherapy side effects

Length of treatment

The length of treatment for immunotherapy vs. chemotherapy varies from patient to patient, and is affected by many different factors specific to the individual and their type of cancer. Immunotherapy may be given over a defined number of treatments or indefinitely, depending on patient responses and whether the patient is receiving treatment as part of a clinical trial.

How long does each treatment take to work?

In the short-term, there can be differences in how long it takes patients to respond to immunotherapy and chemotherapy. For instance, in chemotherapy (and radiation) treatments, targeted tumors may start shrinking immediately. With immunotherapy, it may take longer to see the effects of treatment as the immune system is mobilized to attack tumors. Sometimes, tumors may even appear to grow at first, but in reality this swelling in size can be due to the infiltration of immune cells into tumors. This phenomenon, known as pseudoprogression, isn’t uncommon for immunotherapy, and it doesn’t mean that the treatment isn’t working.

How effective is each treatment?

While chemotherapy treatment effects only last as long as the drugs remain in the body, one of the most exciting and groundbreaking aspects of immunotherapy is that it can provide long-term protection against cancer, due to the immune system’s ability to recognize and remember what cancer cells look like. This immune ”memory” is what makes longer-lasting remissions possible. Clinical studies have shown that beneficial responses to cancer immunotherapy treatment can be durable and can be maintained even after treatment is completed. Additionally, some evidence has revealed that certain types and doses of chemotherapy can enhance immune responses against tumors, thus providing another rationale for combining these treatments in certain settings.

Which cancers can be treated by immunotherapy?

Since immunotherapy takes advantage of the immune system’s natural power to recognize and remember cancer cells, it has the potential to be effective against every type of cancer. Immunotherapy has already led to major advances in the treatment of many types of cancers, and has been approved as a first line of treatment for several. Its effectiveness has also been proven against types of cancer that have been historically resistant to chemotherapies and radiation treatments.

The promise of immunotherapy

Every patient should determine, in consultation with their oncologist and care team, the cancer treatment path that’s right for them, whether that be chemotherapy, immunotherapy, or a combination of these or other types of cancer treatments. Understanding the difference between immunotherapy and chemotherapy is the first step toward making the right decision and finding the best treatment options available.

Whether or not it’s the right treatment for individual patients, spreading awareness of the cutting edge science is an important part of supporting continued research toward a cure. Learn more about why immunotherapy matters and how CRI’s innovation and research has shaped the progress of immunotherapy treatments. We couldn’t make progress in the world of cancer treatment without help—contribute to continued breakthroughs in cancer research and treatment options by making a donation to CRI today.

Updated December 20, 2019