Human papilloma viruses (HPVs) can cause several types of cancer. There are 12 high-risk HPV types: HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59. Two of these, HPV 16 and HPV 18, are responsible for most HPV-related cancers. Low-risk HPV types usually do not cause cancers, but several of the low-risk HPV viruses can cause warts around the genitals, anus, mouth, or throat. Only about 25 percent of 18-45-year-old North Americans are aware that HPVs cause cancers of the mouth and most cases of cervical cancer (JAMA Otolaryngol Head Neck Surg, 2023;149(10):870-877). Furthermore, the HPV vaccination is very effective in preventing these cancers and those who knew of the relationship were the ones most likely to have been vaccinated against HPV.
The Natural History of HPV Infections
Almost all sexually-active people will become infected with HPV within months of becoming sexually active. Around half of these infections are with a high-risk HPV type associated with increased cancer risk. Most HPV infections go away with time, as your immune system usually clears HPV from your body within a year. On the other hand, high-risk HPV infections can persist to cause cancers of the anus, cervix, mouth and throat, penis, vagina and uterus. It can take 5 to 10 years for HPV-infected cervical cells to develop into precancers and about 20 years to develop into full-blown cancer.
How Do You Get HPV?
HPVs are transmitted most frequently by skin-to-skin contact. Condoms reduce skin-to-skin contact but the viruses can pass around condoms. You are at increased risk for suffering HPV-related cancer if you:
• have HPV 16 or HPV 18
• smoke
• have a weakened immune system
• have HIV
• take drugs that suppress your immunity
• have a disease that suppresses your immunity
Indications and Limitations of HPV Vaccination
The HPV vaccination is very safe and is 97 percent effective in preventing cervical cancer and 100 percent effective in preventing genital warts from nine of the highest-risk HPV viruses, but only if it is given before a person is exposed to a specific HPV virus for the first time. Once you are infected with a specific HPV virus, you may keep the virus forever and the vaccine will not get rid of that specific virus. The current recommendation is that vaccination be given to:
• all male and female children by age 11 or 12 (before first sexual exposure)
• everyone by age 26
• everyone at any age who has not had a sexual contact
• HPV vaccination is not generally recommended for everyone older than age 26, but the vaccine is approved for people through age 45
• Everybody else at any age who has not been vaccinated can discuss HPV vaccination with their doctors. Since there are more than 200 different HPV viruses, the vaccine may help prevent infection in everybody who is sexually active at any age, even those who have been previously infected with an HPV virus that is not in the vaccine. It is possible that any sexually-active person may benefit from receiving the vaccine.
HPV May Cause Many Cases of Prostate Cancer
The American Cancer Society reports that one in nine men will be diagnosed with prostate cancer in his lifetime. A review of 26 studies on HPV and prostate cancer found that men with prostate cancer are at higher risk than men without prostate cancer to be infected with high-risk HPV. Indeed, 22 percent of men with prostate cancers were infected with HPV (Infect Agents Cancer, 2020;15:41). Furthermore, this study also found that the HPV types 16 and 18, which are most likely to cause cervical cancer in women, are found in normal, benign, and malignant prostate tissues.
My Recommendationns
Every sexual encounter with a different person markedly increases your chances for infection with an HPV virus that may cause cancer. Of the more than 200 HPV viruses, fewer than 20 put you at significant risk for developing cancer. The present HPV vaccination helps prevent HPV-induced cancer, but it works only if you get the vaccine before you are exposed to that virus. After you are infected with a high-risk HPV cancer-causing virus, it is too late for the vaccine to prevent that infection. Condoms help to reduce HPV spread, but cannot completely prevent the skin-to-skin contact that transmits the virus.
