A cancer vaccine is a vaccine that either treats existing cancer or prevents development of a cancer. Vaccines that treat existing cancer are known as therapeutic cancer vaccines. There are currently no vaccines able to prevent all cancers, however vaccines against some oncoviruses have proven extremely effective.
Some types of cancer, such as cervical cancer and some liver cancers, are caused by viruses (oncoviruses), and traditional vaccines against those viruses, such as HPV vaccine and hepatitis B vaccine, will prevent those types of cancer. These anti-viral vaccines are not further discussed in the rest of this article. Other cancers are to some extent caused by bacterial infections (e.g. stomach cancer and Helicobacter pylori) and traditional vaccines against cancer-causing bacteria are also not discussed in this article.
Scientists are continuing research and development of vaccines against other types of cancer. Some researchers believe that cancer cells routinely arise and are destroyed by the healthy immune system; and that cancer forms when the immune system fails to destroy them.
Human papilloma virus (HPV) vaccines are vaccines that prevent infection by certain types of human papillomavirus. Available vaccines protect against either two, four, or nine types of HPV. All vaccines protect against at least HPV 16 and 18 that cause the greatest risk of cervical cancer. It is estimated that they may prevent 70% of cervical cancer, 80% of anal cancer, 60% of vaginal cancer, 40% of vulvar cancer, and possibly some mouth cancer. They additionally prevent some genital warts with the vaccines against 4 and 9 HPV types providing greater protection.
The World Health Organization (WHO) recommends HPV vaccines as part of routine vaccinations in countries that can afford them, along with other prevention measures. The vaccines require two or three doses depending on how old the person is. Vaccinating girls around the ages of nine to thirteen is typically recommended. The vaccines provide protection for at least eight years. Cervical cancer screening is still required following vaccination. Vaccinating a large portion of the population may also benefit the unvaccinated. In those already infected the vaccines do not help.
Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal vaginal bleeding, pelvic pain, or pain during sexual intercourse. While bleeding after sex may not be serious, it may also indicate the presence of cervical cancer.