Cancer Vaccines and Their Side Effects

Most of us know about vaccines given to healthy people to help prevent infections, such as measles and chicken pox. These vaccines use weakened or killed germs like viruses or bacteria to start an immune response in the body. Getting the immune system ready to defend against these germs helps keep people from getting infections.

Most vaccines used to treat cancer work the same way, but they make the person’s immune system attack cancer cells. The goal is to help treat cancer or to help keep it from coming back after other treatments. But there are also some vaccines that may actually help prevent certain cancers.

Vaccines to help prevent cancer

Some cancers are caused by viruses. Vaccines that help protect against infections with these viruses might also help prevent some of these cancers.

• Some strains of the human papillomavirus (HPV) have been linked to cervical, anal, throat, vaginal, vulvar, and penile cancers. In fact, most cervical cancers are caused by infection with HPV. Vaccinating children and certain young adults against HPV helps protect against cervical cancer and the other 5 cancers HPV can cause. Read more in Protect Against HPV.
• People who have chronic (long-term) infections with the hepatitis B virus (HBV) are at higher risk for liver cancer. Getting the vaccine to help prevent HBV infection may lower some people’s risk of getting liver cancer.

These are traditional preventive vaccines that target the viruses that can cause certain cancers. They may help protect against some cancers, but they don’t target cancer cells directly because cancer cells have not yet been formed or found.

These types of vaccines are only useful for cancers known to be caused by infections. But most cancers, including colorectal, lung, prostate, and breast cancers, are not thought to be caused by infections.

Vaccines to treat cancer

Cancer treatment vaccines are different from the vaccines that work against viruses. These vaccines try to get the immune system to mount an attack against cancer cells in the body. Instead of preventing disease, they are meant to get the immune system to attack a disease that already exists.

Some cancer treatment vaccines are made up of cancer cells, parts of cells, or pure antigens (certain proteins on the cancer cells). Sometimes a patient’s own immune cells are removed and exposed to these substances in the lab to create the vaccine. Once the vaccine is ready, it’s injected into the body to increase the immune response against cancer cells.

Vaccines are often combined with other substances or cells called adjuvants that help boost the immune response even further.

Cancer vaccines cause the immune system to attack cells with one or more specific antigens. Because the immune system has special cells for memory, it’s hoped that the vaccine might continue to work long after it’s given.

• Sipuleucel-T (Provenge):This drug is used to treat advanced prostate cancer that is no longer being helped by hormone therapy. Side effects are usually mild and can include fever, chills, fatigue, back and joint pain, nausea, and headache. A few men may have more severe symptoms, including problems breathing and high blood pressure.

• Talimogene laherparepvec (T-VEC): This vaccine is approved to treat advanced melanoma skin cancer. It is made from a herpes virus that has been altered in the lab to produce a substance that the body normally produces, called a cytokine. This cytokine boosts the immune system and can cause flu-like symptoms for a short time.

Other vaccines

Other types of cancer vaccines have shown some promise in clinical trials, but they are not yet approved in the U.S. to treat cancer.