October 07, 2019
Modern Western medicine has benefited society with antibiotics, antihypertensive medications and vastly improved trauma management. These have resulted in dramatic decreases in morbidity and mortality for millions of patients. The concept of immunization was born in 1798 when Edward Jenner inoculated a young boy against smallpox. The vaccine process has since resulted in the eradication of smallpox, as well as dramatic reductions in the number of deaths due to infectious diseases, including measles, pertussis, polio, streptococcal and hemophilia meningitis.
Preventing cancer through vaccination
About 30 years ago, vaccines took a dramatic new direction with the introduction of an inoculation that could prevent cancer: the hepatitis B vaccine. This vaccine targeted one of the leading causes of acute hepatitis and hepatocellular carcinoma, the hepatitis B virus.
Infection with this virus can lead to acute symptoms (hepatitis), but can also move to a silent, carrier state in an infected person. If a woman who is a carrier becomes pregnant, she can pass the virus to her unborn child unknowingly. Eventually, both the mother and the child are at a greatly increased chance of developing liver cancer due to the hepatitis B virus. The hepatitis B vaccine was the first vaccination that was effective against cancer, an amazing advance in personal and public health.
In 2006, the second anticancer vaccine, the human papillomavirus vaccine, was introduced. Most sexually active people will get HPV at some point in their lives. This means that everyone is at risk for the potential outcomes of HPV, including cervical, ovarian, anal, esophageal and penile cancer.
In the United States, there are as many as 35,000 new HPV-related cancer cases diagnosed annually, leading to about 8,000 deaths. The worldwide burden of HPV-related cancers is much higher. These cancers are insidious and are very difficult to treat as they are often not detected until they are advanced. HPV-associated cancers are often diagnosed in younger patients – women with cervical cancer and men with esophageal cancer.
How does the HPV vaccine work?
While there are hundreds of types of HPV, the vaccines have been developed to fight the types of HPV associated with cancer. When introduced in 2007 in the United States, the vaccine was initially approved for girls ages 11 and older. As with the hepatitis B vaccine, it is essential to vaccinate people prior to exposure to the virus. However, once the virus has infected a cell, the vaccine is not effective at killing the virus. Instead, once inside a target cell, the virus can eventually cause cellular changes that turn a normal cell into a cancerous cell. Thus, while the HPV virus can be spread by several routes, including sexual contact, it is crucial that adolescents and young adults be vaccinated prior to virus exposure.
Because men are often silent carriers of HPV (leading to the spread of the virus among women or esophageal and penile cancer in men), the vaccination program was expanded to include males 11 years or older. Currently, the vaccination schedule calls for 2 doses to be administered to all eligible males and females beginning as early as age 9. A 3-dose schedule remains recommended for persons who initiate the vaccination series at ages 15 through 26 and for those who are immunocompromised. Studies from several countries where the vaccine has been administered for more than 20 years are beginning to show the predicted reductions in cancers caused by the virus.
As more people are vaccinated against HPV, resistance to HPV infection will build and there will be a corresponding decline in the rates of cervical, ovarian, esophageal, anal and penile cancers. These cancers are predicted to decline in the same way that polio, smallpox, pertussis and other infectious diseases have as a result of vaccination.
Potential side effects
There is no such thing as a completely risk-free therapy. Despite concerns about vaccination, vaccines have been an overwhelmingly positive influence on the health of people around the world. Similarly, there are concerns about the safety of the HPV vaccine. Such concerns are appropriate with any new medical intervention. Dozens of studies involving millions of patients have been conducted and, to date, have revealed no serious side effects associated with the HPV vaccine.
With more than 85 million doses of the vaccine administered in the United States alone, no serious side effect has been tied to receiving the vaccine. This does not mean that we won't continue to search for rare side effects that may affect a few patients. It does, however, indicate that the HPV vaccine is extremely safe and that the risk-to-benefit ratio clearly favors giving the vaccine to eligible patients.
As with many vaccines, there are a few patients who should not receive the vaccine due to an underlying medical condition – for instance, an immunodeficiency that would not allow their body to respond effectively to the vaccine. However, those circumstances are rare and can be identified by appropriate screening.
The HPV vaccine: It could be a matter of life or death
You have the opportunity to protect your children from certain kinds of cancers – and it’s in the form of a simple vaccine. Why wouldn’t you want to protect them? Currently, about 8,000 people die every year from HPV-related cancers. If everyone got the vaccine, over the next 20 to 30 years, we could see HPV cancers become a disease of medical history, much like smallpox.