Vaccines Help In the Fight Against Cancer
Feb 04, 2014
Vaccines do more than just boost our immune system against dangerous bacteria, viruses or parasites. They can also help prevent and treat various types of cancer.
In acknowledgement of World Cancer Day, we would like to highlight the two broad types of cancer vaccines.
- Preventive (or prophylactic) vaccines, which are intended to prevent cancer from developing in healthy people; and
- Treatment (or therapeutic) vaccines, which are intended to treat an existing cancer by strengthening the body’s natural defenses against the cancer.
According to the National Cancer Institute, these medicines belong to a class of substances known as biological response modifiers. Biological response modifiers work by stimulating or restoring the immune system’s ability to fight infections and disease. Currently in the United States there are two types of cancer preventive vaccines that are available (HepB and HPV vaccines) and one cancer treatment vaccine that has recently become available.
Hepatitis B Virus (HBV) Vaccine
Although a safe and effective hepatitis B vaccine has been available since 1982, the hepatitis B virus (HBV) remains a leading cause of liver cancer. Unfortunately, about 1 in 20 people are living with a chronic HBV infection (that’s about 350 million individuals), and the virus is also killing 600,000 people every year worldwide. That means every 50 seconds someone dies from this vaccine-preventable disease.
It’s important to recognize that HBV can be transmitted in a number of different ways and spreads when the blood, semen or other bodily fluid of an infected person enters the body of someone who isn’t infected. Often a chronically infected mother, unaware of her infection, silently passes the virus on to her child during the birthing process. The virus can also be transmitted through direct contact with infected blood through wound contact, reusing or sharing needles used for tattoos, piercings, acupuncture, or injection drugs, reusing syringes or medical devices, sharing razors or toothbrushes that have been contaminated by blood, and blood transfusions.
A person infected with HBV can also transmit the disease through unprotected sex, and while the use of condoms can reduce the risk of infection, it doesn’t fully eliminate the possibility. People at high risk of infection also include travelers who visit endemic areas, people who frequently require blood or blood products, dialysis patients, recipients of solid organ transplantations, health-care workers and others who may be exposed to blood and blood products through their work.
The likelihood that a hepatitis B infection will become chronic depends upon the age at which a person becomes infected. Statistics show that 80–90% of infants who are infected during the first year of life, go on to develop chronic infections which is why infants are recommended to receive the Hepatitis B vaccine at birth.
Experts agree that the 3-shot hepatitis B vaccine can provide lifelong protection against HBV, thus eliminating the most common cause of liver cancer. The vaccine is not only proven safe, but is believed to be 95% effective at preventing HBV infection. Further more, the vaccination series can be started at any age and does not require any boosters. In fact, the vaccine is so effective at preventing HBV and liver cancer that the World Health Organization (WHO) has declared it the world’s first “anti-cancer vaccine.”
Human Papillomavirus (HPV) Vaccine
It may come as a surprise to some that the HPV infection is believe to be the most commonly sexually transmitted infection in the U.S. An estimated 20 million persons are currently infected, and an estimated 6.2 million new HPV infections occur annually. HPV infection is especially common among adolescents and young adults, with rates as high as 64% in adolescent girls and up to 75% of new infections occuring among persons 15–24 years of age. It’s believed that as many as 80-90% of all sexually active women will have an HPV infection at some point in their lives.
While some of these infections will clear on their own in time, others will eventually develop into various types of cancer. While there are over a 100 different types of HPV, about 20 of those are associated with cervical cancer, the second leading cause of cancer deaths in U.S. women. On a global level, each year 500,000 women are diagnosed with cervical cancer worldwide and 250,000 will die of their disease.
Fortunately, the FDA has approved two HPV vaccines that are highly effective at preventing HPV strains 16 and 18, which are known to cause approximately 70% of all cases of cervical cancer worldwide. These two strains (16 and 18) are also know to cause some vaginal, vulvar, anal, penile cancer among men, and oropharyngeal (throat) cancers among both men and women. While there are at least 17 other types of HPV that are responsible for the remaining 30% of cervical cancer cases, it’s clear that the widespread immunization with the current HPV vaccines can be effective in preventing the overwhelming majority of cervical cancer cases.
It should be noted that in the U.S., the Advisory Committee for Immunization Practices (ACIP) recommends routine HPV vaccination of both males and females at 11 or 12 years of age and this is why. First, it’s possible to be infected with HPV the first time a person has sex. Since studies show that 7% of kids aged 12 to 13 have had sex, 28% by age 15, 33% by age 16, 48% by age 17, 61% by age 18 and 71% by age 19, it’s best if the vaccine series is completed before sexual activity begins. Additionally, studies show that the vaccine produces a greater immune response to fight infection when given at this age, compared to receiving the vaccine at a later age.
For more discussion as to the importance of the HPV vaccine and myths that have kept some parents from vaccinating there children, see another Shot of Prevention post here.
First FDA Approved Cancer Treatment Vaccine
When it comes to discussing cancer vaccines, it’s important to note that in April 2010, the FDA approved the first cancer treatment vaccine for use in some men with metastatic prostate cancer. This vaccine was designed to stimulate an immune response to prostatic acid phosphatase (PAP), an antigen that is found on most prostate cancer cells. In a clinical trial, the vaccine (referred to as sipuleucel-T) increased the survival of men with a certain type of metastatic prostate cancer by about 4 months. Interestingly enough the vaccine is customized to each patient and more information and details regarding this vaccine can be found on the National Cancer Institute website.
What Lies Ahead for Preventive and Treatment Cancer Vaccines
It’s encouraging to see that there are several types of cancer vaccines that are currently being studied in clinical trials. Simply click the cancer names in the list below and you will be linked to search results from the National Cancer Institute’s clinical trials database.
Active Clinical Trials of Cancer Treatment Vaccines by Type of Cancer:
- Bladder Cancer
- Brain Tumors
- Breast Cancer
- Cervical Cancer
- Hodgkin Lymphoma
- Kidney Cancer
- Lung Cancer
- Multiple Myeloma
- Non-Hodgkin Lymphoma
- Pancreatic Cancer
- Prostate Cancer
- Solid Tumors
Active Clinical Trials of Cancer Preventive Vaccines by Type of Cancer:
If you would like more information about cancer vaccines, visit the National Cancer Institute here and the American Cancer Society here.
This guest post was written by Alethea Mshar out of concern for her son Ben. A version of this post originally appeared on her blog Ben’s Writing, Running Mom. Like all parents, my child’s health...
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