During your cancer journey, you may hear your care team talk about treatments like immunotherapy and chemotherapy. While both use drugs to stop cancer from growing, they work in very different ways—and it’s normal to feel confused about what each one does. Understanding the difference between these treatments may help you feel more informed and confident as you move forward with your care.
This article will explore:
- What is immunotherapy?
- How is an immunotherapy drug chosen?
- What is chemotherapy?
- How are chemotherapies chosen?
- Is immunotherapy chemo?
- Chemotherapy vs. immunotherapy side effects
If you’ve been diagnosed with cancer and are interested in getting a second opinion of your diagnosis or treatment options, call us or chat online with a member of our team.
What is immunotherapy?
Immunotherapy is a type of cancer treatment that helps your own immune system fight cancer.
Your immune system is your body’s natural defense—it works to find and destroy things that don’t belong, like viruses or bacteria. But sometimes, cancer cells find ways to hide from it.
Immunotherapy works by "boosting" your immune system or helping it recognize and destroy cancer cells more effectively.
Common types of immunotherapy include:
Checkpoint inhibitors: Some cancer cells send out signals that trick the immune system into ignoring them. Checkpoint inhibitors block that signal, allowing the immune system to see and attack the cancer.
Cytokines: These small, natural proteins carry messages between cells and guide your immune system to attack cancer.
Chimeric antigen receptor (CAR) T-cell therapy: Doctors take your own infection-fighting T cells, reprogram them in a lab to recognize cancer, and put them back in your body. These amplified T cells are now trained to seek out and destroy cancer cells.
Cancer vaccines: There are preventive and therapeutic cancer vaccines. The former helps prevent cancers caused by viruses (like HPV or hepatitis B), while the latter helps train the immune system to recognize and attack cancer cells more precisely.
Monoclonal antibodies: These artificially designed proteins bind to cancer cells and mark them so your immune system can detect and destroy them.
Ultimately, the goal of immunotherapy is to help your body make a strong group of immune cells—especially T cells—that locate and attack cancer. T cells are a special kind of white blood cell that normally protects you from infections. Though immunotherapy doesn’t work for every type of cancer or every patient, for some, it can be a powerful part of treatment.
How is an immunotherapy drug chosen?
When it comes to choosing an optimal immunotherapy drug, your care team looks at several factors, including your specific cancer type, how your cancer is behaving and your overall health. Following is a breakdown of important considerations.
Cancer type and stage: Not all cancers respond to immunotherapy. Doctors first consider whether your type of cancer is known to respond to it—such as melanoma and lung, kidney, bladder and certain blood cancers. They’ll also look at the stage of your cancer and whether it’s early, advanced or has spread to other parts of the body (metastasized).
Biomarker testing: Your oncologist may test your tumor or blood for biomarkers, which are specific signs that help predict if immunotherapy will work. Three of particular importance include:
- PD-L1 levels – a protein some tumors use to hide from the immune system.
- Microsatellite instability (MSI-H) or mismatch repair deficiency (dMMR) – signs that cancer cells have faulty DNA repair systems.
- Tumor mutational burden (TMB) – a way of measuring how many genetic changes (mutations) a tumor has in its DNA; the more mutations there are, the more likely immunotherapy may help.
Your overall health: Some immunotherapies may cause strong immune responses, so doctors also consider:
- Your age
- Any autoimmune conditions
- How well your organs are working
- Previous treatment
What is chemotherapy?
Chemotherapy works by targeting fast-growing and dividing cells in the body—traveling through your bloodstream, so they can reach cancer cells almost anywhere in the body, not just in one location. That’s why chemo is called a systemic treatment. There are more than 100 different chemotherapy drugs.
Oncologists use chemo to shrink tumors before surgery or radiation; kill remaining cancer cells after surgery; treat cancer that has spread or relieve symptoms in advanced stages.
Chemotherapy drugs are broadly classified based on how they work. The main categories include:
- Alkylating agents
- Plant alkaloids (topoisomerase inhibitors and mitotic inhibitors)
- Anti-metabolites
- Anti-tumor antibiotics
- Corticosteroids
- Platinum-based drugs
How are chemotherapies chosen?
Simply stated, chemotherapy isn’t one-size-fits-all. It requires a personalized approach. That’s why oncologists consider tumor type and behavior, the patient’s health and what science and experience show to be most effective. Considerations include:
- Some chemo drugs work better on specific cancer cell types.
- Tumor location and whether it has spread affect drug choice.
- Fast-growing cancers may need stronger chemo; slow-growing ones may not.
- Tumor gene mutations may guide which drugs are most effective.
- Patient age, health and organ function impact which treatments are safe.
- Side effects vary, so doctors balance effectiveness with tolerability.
Is immunotherapy chemo?
The key difference between immunotherapy and chemotherapy is the way they work.
They have the same goal but accomplish it differently. Immunotherapy boosts your immune system to recognize and attack cancer cells more precisely, while chemotherapy kills fast-growing cancer cells directly, often affecting healthy cells as well.
Chemotherapy vs. immunotherapy side effects
Any form of cancer treatment may have side effects. Because chemotherapy doesn’t target just cancer cells, but all cells that divide rapidly, it may also damage fast-replicating hair, skin, blood and intestinal cells. That’s why hair loss, anemia and nausea are common side effects of chemotherapy treatments.
With immunotherapy, some side effects are caused by the drugs putting your immune system into overdrive, sometimes to the extent that your immune system attacks your organs.
Chemotherapy and immunotherapy may sometimes cause similar side effects, including those listed below.
- Fatigue
- Nausea and vomiting
- Loss of appetite
- Diarrhea
- Mouth sores
- Skin changes like rashes, dryness or itching
- Increased risk of infection
Other symptoms—some flu-like—are also possible following immunotherapy. These include:
- Fever or chills
- Headaches
- Dizziness
- Muscle aches or joint pain
- High or low blood pressure
- Fluid buildup (lymphedema), usually in the legs
Other chemotherapy-related side effects may include:
- Weight loss or weight gain
- Anemia
- Bruising and bleeding
- Nerve problems, such as numbness, tingling and pain
- Fertility issues
- Weakened immune system, which may lead to infections
The side effects of immunotherapy generally become less severe after the first treatment. For chemotherapy, most side effects subside once treatment is completed.
“One advantage of chemo is that the side effects appear when the treatment starts, but once you stop the chemo, most of them go away. They’re dose-dependent, they’re timing-dependent,” says Kevin Zhang, M.D., a medical oncologist at City of Hope® Cancer Center Chicago. “When you’re using immunotherapy, you may have no side effects, which is optimal, but on the other hand, you may have those random idiosyncratic reactions that are autoimmune phenomena that happen because the immune system was awakened. The good thing is we know how to handle those side effects, too. We’re basically toning down the system in those cases.”
Does immunotherapy cause hair loss?
In most cases, immunotherapy does not cause hair loss, which is a common side effect of chemotherapy. That’s because immunotherapy works differently — it helps your immune system recognize and attack cancer cells, rather than targeting all rapidly dividing cells, including those in hair follicles.
Though rare, hair changes are still possible. Some people may experience thinning or patchy hair loss, especially if they develop certain immune-related side effects like inflammation of the skin (including the scalp). These side effects are usually manageable and often reversible.
If you’ve been diagnosed with cancer and are interested in getting a second opinion of your diagnosis or treatment options, call us or chat online with a member of our team.