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Updated on August 20, 2025
Colorectal cancer is the third most common form of cancer in the United States. It refers to cancer of the colon or the rectum, which are sections of the large intestine, located in the lower part of the gastrointestinal tract.
Immunotherapy is a treatment option for early- and advanced-stage colorectal cancers that test positive for microsatellite instability (MSI) and changes in mismatch repair (MMR) genes. These are gene changes that can be discovered during molecular testing. A positive result indicates that a cancer is likely to respond to immunotherapy.
Unlike chemotherapy or targeted therapy drugs, immunotherapies do not attack cancer cells directly—they increase the immune system’s ability to detect and destroy cancer cells.
Subcutaneous immunotherapy
Cancer immunotherapies are typically administered with an intravenous (IV) infusion, where the drug is delivered into the bloodstream using a needle inserted into a vein.
With subcutaneous immunotherapy, the immunotherapy drug is delivered into a layer of fatty tissue directly below the skin, called the subcutaneous layer. The subcutaneous layer is a useful route of administration for medications. From the subcutaneous layer, a medication will be absorbed into the lymphatic system, the body’s network of vessels, lymph nodes, and organs that transport immune cells and remove unwanted substances.
Subcutaneous immunotherapy is a new and emerging treatment option that is expected to expand in the future. If you or a loved one is living with colorectal cancer and immunotherapy is a treatment option, it may be worth discussing subcutaneous immunotherapy with your healthcare team.
With that in mind, here are some questions to help you get started.
What subcutaneous immunotherapy drugs are available?
Your first question will be whether the subcutaneous immunotherapy drugs that are available are a good fit for your diagnosis and treatment needs. Currently, there is only one subcutaneous immunotherapy approved for colorectal cancer.
What will an injection appointment be like?
A subcutaneous injection typically takes 3 to 5 minutes to administer. If you and your healthcare providers decide that subcutaneous immunotherapy is a treatment option, ask what you can expect at injection appointments, including what the injection process is like, how long you can expect to be at an appointment, and any special instructions you need to follow before and after the appointment.
Where will the injections be administered?
Subcutaneous injections are typically administered in the abdomen or thigh.
Where can you go for an injection appointment?
Subcutaneous immunotherapy offers more flexibility for appointment locations, and injections can be administered at a healthcare provider’s office. It does not require a visit to a hospital or infusion center, which is necessary for IV infusions.
What is the risk of side effects?
All cancer treatments cause side effects. The side effects will vary depending on the type of treatment, the specific drug being used, and in some cases, how that drug is administered. Fatigue, itching, cough, joint pain and muscle pain, and GI distress are common immunotherapy side effects, but your healthcare providers can explain the risk of side effects in greater detail. Your healthcare providers can also recommend medications and strategies to ease side effects.
Are there contraindications or potential drug interactions?
Contraindications are health conditions that make a therapy potentially unsafe and inadvisable. Drug interactions are unintended effects that occur from taking two drugs simultaneously. Your healthcare team should review your medical history, and they should have an up-to-date list of all medications you are taking (prescription, over-the-counter drugs, and supplements).
How can you expect to feel during and after an injection?
Ask your healthcare providers about how you can expect to feel immediately after an injection and in the days after. Ask if they have recommendations, such as having someone there to drive you home after the injection or taking a day off work.
How long will this part of treatment last?
Ask how long you will be taking the immunotherapy, what you can expect to feel like during this time, and any lifestyle adjustments you need to make—for example, precautions to prevent infections, or changes to diet and daily habits.
How often will treatments need to be administered?
Ask your healthcare providers how often you will come in for injections. Injections are typically given every two weeks or every four weeks depending on dosage. Also ask how often you will need to come in for checkups and exams.
Preparing for your appointments
The questions above are intended as a starting point. Take time to think about what you want to know and write down a list of questions for your next appointment. It can also help to bring a loved one to your appointment, both as emotional support and to help you take notes.
Remember, your healthcare team will be your best source of information, and you are also an important source of information to your healthcare team. Knowing your concerns and questions can help your healthcare team provide you with better care.
