A variety of viruses, bacteria, and parasites have been found to increase the risk of
several types of cancer. In developing countries where many types of infections are
highly prevalent, infections are linked to 15% to 25% of cancers. The proportion of
new cancers in the U.S. that are ascribed to infectious agents is about 4%.
There are several ways that infections can lead to a higher risk of cancer: by causing
inflammation, by immune system suppression, or by damaging a cell’s DNA and
causing mutations. Although infections can raise a person’s risk of cancer, most
people with the infections that sometimes cause cancer never develop cancers.
Viruses reproduce by entering a living cell, inserting their own DNA or RNA, and
causing the cell to synthesize more viruses. This process can affect a normal cell’s
genes and may increase the risk of the cell becoming cancerous. Vaccines against
several viruses have been developed to prevent a few human cancers. They must be
given before the person is exposed to the cancer-promoting virus.
Human papillomaviruses (HPVs)
Human papillomaviruses (HPVs) cause almost all cases of cervical cancer. They
can also cause warts on the skin, mouth, genitals, and larynx and cause some cancers
of the penis, anus, vagina, vulva, mouth, and throat. There are more than 100
types or strains of HPV, a virus that is spread by personal contact. More than 40 of
them can be spread through sexual contact, and they are common in sexually active
people. A dozen types are known to cause cancer. Although HPV infection is common,
most people infected with HPV do not develop cancer.
Cervical cancer remains common worldwide but is much less frequent in the U.S.
because of prevention through widespread screening with Pap tests. When a Pap
test detects infected pre-cancerous cells, they can be removed or destroyed before
they become cancerous. Frequently, treatment is not needed because the body’s
immune system controls the HPV infection and eliminates both the virus and the
abnormal pre-cancerous cells. Testing for the presence and type of HPV strain can
also guide treatment by revealing if one of the high-risk virus types is present in the
cervix.
Vaccines against HPV102
Gardasil 9® protects against nine types of HPV. It usually prevents the cervical,
vulvar, vaginal, and anal cancers caused by HPV, and genital warts caused by HPV.
With two or three doses (depending on age), Gardasil 9® protects against the seven
high-risk types of HPV responsible for more than 90% of cervical cancers and two
other HPV types accounting for 90% of genital warts. It is approved and recommended
for use in females age nine to 45 prior to their becoming sexually active
and infected with HPV. Gardasil 9® also protects against two strains of HPV virus
that cause genital warts and has been approved for use in boys and young men to
prevent anal cancers, genital warts and to prevent them from passing on HPV to
their sexual partners.
Hepatitis B virus (HBV) and hepatitis C virus (HCV)
HBV and HCV are transmitted from person to person. HBV can be transmitted by
blood, sharing needles, unprotected sex, and body fluids. The rate of transmission
of HCV by unprotected sex and body fluids is low. Usually, transmission occurs
through contact with blood, for example, by sharing unsterilized needles. A small
proportion of the cases of viral hepatitis caused by HBV and HCV become chronic
and increase a person’s risk for developing cirrhosis, liver failure, and liver cancer. About 40% of liver cancers in the U.S. are linked to HBV or HCV infection.
Hepatitis B has become less of a problem in the U.S. because of the widespread
use of the hepatitis B vaccine. Treatment of chronic hepatitis B does not eliminate
the virus, but it can suppress HBV replication and bring about remission of liver
disease before the development of cirrhosis and liver cancer. However, there is no
HCV vaccine, and an estimated 3.2 million people in the U.S. have chronic HCV
infection. It is estimated that 75% of them do not know they are infected. Treating
chronic hepatitis C infection with drugs that have a high cure rate is now possible.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel
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