Vaccines That Prevent Cancer
The U.S. Food and Drug Administration (FDA) has approved two types of vaccines that can prevent cancer in healthy people. One is used to protect against the hepatitis B virus, which can cause liver cancer as well as cirrhosis (scarring) of the liver. The second protects against human papillomavirus (HPV), which is responsible for almost all cervical cancers and more than half of oropharyngeal (throat) cancers. HPV is also linked to some other cancers and is responsible for 5% of all cancers worldwide, according to the U.S. National Institutes of Health.
The hepatitis B and HPV vaccines don’t target cancer cells directly; instead, they prevent the infections that lead to specific cancers. Most common cancers, such as colorectal, lung, prostate, and breast cancers, are not caused by viral infections.
The hepatitis B and HPV vaccines are made from antigens (substances that are present on the surface of a virus) that the immune system will recognize as foreign. These antigens do not cause a viral infection, but they train the immune system to fight off the virus if the vaccinated person is exposed to it later.
The hepatitis B vaccine
Both the U.S. Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics recommend that all infants at birth and unvaccinated children up to age 18 years receive the hepatitis B vaccine. Three shots are required to get lifetime protection from hepatitis B. The second shot is given at least 1 month after the first, and the third injection is given at least 6 months after the first.
The CDC also recommends that unvaccinated adults in high-risk groups be vaccinated against hepatitis B. High-risk groups include health care professionals and emergency personnel, patients who have kidney disease or are receiving dialysis, sexually active people who are not in a monogamous relationship, and anyone living with an infected person. Travelers to regions where hepatitis B is common (Asia, Africa, South America, the Pacific Islands, Eastern Europe, and the Middle East) and families considering international or domestic adoption should also be vaccinated.
The HPV vaccine
Two vaccines—Gardasil and Cervarix—have been approved by the FDA to prevent HPV infections. Both Gardasil and Cervarix protect against HPV types 16 and 18, which cause about 70% of cases of cervical cancer as well as some vaginal, vulvar, anal, penile, and oropharyngeal cancers. Gardasil also protects against two other HPV types, 6 and 11, which are responsible for about 90% of genital warts in males and females. Both of these vaccines are available to females, but only Gardasil has been approved by the FDA for use in males. Either vaccine is given in a series of three shots over 6 months.
The CDC recommends that girls and boys receive the HPV vaccine when they are 11 or 12 years old. The HPV vaccine also is recommended for teenaged boys and girls who did not get the shots when they were younger and for unvaccinated women 26 years or younger and unvaccinated men 21 years or younger. Other groups who should get the vaccine are gay and bisexual men and adults 26 years or younger with compromised immune systems. Although the HPV vaccine can prevent the virus that causes cervical cancer, it does not substitute for routine cervical cancer screening.
The hepatitis B and HPV vaccines have been widely used and shown to be safe, with only mild to moderate side effects. The hepatitis B vaccine may cause soreness in the vaccinated arm and a low fever. The most common side effects of the HPV vaccines are soreness, swelling, and redness at the injection site. Less common side effects of the HPV vaccine are fever and headaches, and occasionally people experience dizziness or fainting shortly after the injection.
— K. Stuyck
Other articles in OncoLog, March 2014 issue: