Immunotherapy and chemotherapy are both techniques used to treat cancer. The difference between each treatment option can be unclear; however, the main differentiating factor is the way in which these treatments target cancer. Chemotherapy uses drugs to target and kill fast-growing cells, and immunotherapy uses the body’s immune system to slow, stop, and kill cancerous cells.

What Is Immunotherapy?

Immunotherapy is a cancer treatment that’s becoming increasingly popular for aggressive cancers, such as mesothelioma. Currently, immunotherapy is only available through clinical trials, so not all patients can participate in this form of treatment. It has shown success in targeting tumor growth and symptoms with mesothelioma, skin cancer, lung cancer, breast cancer, and many others.

Immunotherapy focuses on the body’s immune system. Our immune system is composed of T cells, which recognize foreign molecules and seek to get rid of them. This is how we fight off everything from colds to infections. Cancer cells often resemble normal cells, making it difficult for immune cells to recognize and destroy them.

How Does Immunotherapy Work?

The main goal of immunotherapy treatment is to either restore immune system functionality or to improve it. This can then slow, stop, or kill tumor cells. This type of cancer treatment is commonly used in combination with conventional treatments, such as surgery, chemotherapy, and radiation therapy. For certain cancers like mesothelioma, immunotherapy may be an option for patients that aren’t responding to standard treatment options.

There are multiple types of immunotherapies that can be used to fight cancer, categorized as passive or active. Active therapies rely on the body’s immune system to fight the tumor, whereas passive takes substances created outside of the body, then inserts them into the body to kill the cancerous cells. Immune checkpoint inhibitors and monoclonal antibodies are two of the most popular forms of immunotherapies being used, both passive.

What Is Chemotherapy?

Chemotherapy, also known as “chemical therapy,” involves the administration of medication to target and destroy cancer cells. The main goals of chemotherapy are to prevent cancer cells from multiplying and to reduce cancer symptoms. There are many different chemotherapy drugs available, and chemotherapy can be used independently or in conjunction with other treatment options, which is referred to as multimodal treatment. While immunotherapy is only available to those accepted into clinical trials, chemotherapy is FDA approved and considered a standard of care.

How Does Chemotherapy Work?

There are two types of chemotherapy, each different in how they are administered. Common side effects also differ with each type.

  • Systemic chemotherapy: Administered intravenously or in pill form, traveling through the bloodstream throughout the entire body to target and kill cancerous cells
  • Intraoperative chemotherapy: Applied directly to tumor formations during surgery (examples include intrapleural chemotherapy and heated intraperitoneal chemotherapy, also referred to as HIPEC)

Since systemic chemotherapy travels throughout the body, more cells are affected, therefore causing more side effects than intraoperative. Chemotherapy doesn’t only target foreign cells, but can also target healthy cells, causing a range of side effects, such as hair loss and nausea.

Differences Between Immunotherapy and Chemotherapy

While chemotherapy and immunotherapy are both popular treatment options for cancer, immunotherapy thrives off of the body’s immune system, while chemotherapy introduces new medications to target and kill cells. While immunotherapy is not yet a traditional mode of treatment, it’s success in clinical trials and FDA approval for a growing list of cancers show promise towards adoption as a first-line treatment option.


  • Only available through clinical trials
  • Restores or stimulates the immune system
  • Uses the body’s immune system to target cancer cells
  • Limited range of side effects


  • Available as a standard treatment option
  • Involves the application of drugs to the body
  • Uses medication to kill cells throughout the body or at a targeted region
  • Wider range of side effects

Is Immunotherapy More Effective Than Chemotherapy?

There are a variety of influencing factors that determine the efficacy of different treatment methods, such as cancer type, staging, and patient health.

For example, malignant pleural mesothelioma is an extremely aggressive cancer with a low life expectancy. Multimodal treatment is common, incorporating surgery, chemotherapy, and radiation. However, immunotherapy might be more effective than traditional mesothelioma treatment options. Drugs like Keytruda® have successfully extended life expectancy for some mesothelioma patients in clinical trials.

Ultimately, the best treatment plan for a cancer patient is going to vary, and the best option is to talk to a medical professional. They will gather all of the patient’s history, run a variety of tests, and determine the best way to slow or stop the growth of cancer, while also addressing symptoms.