Human Papillomavirus, commonly known as HPV, is the most common sexually transmitted infection in the world. HPV is so common that the majority of sexually active people will become infected with it at some point in their life, especially in developing countries. While the number of annual cases has been reduced substantially with the availability of the HPV vaccine, HPV still poses a substantial threat to public health worldwide, as it has been associated with around 99% of cases of cervical cancer and 90% of cases of anal cancer.
This sounds extremely scary, particularly given that HPV is so common. Most cases of HPV, however, will not lead to such drastic outcomes - this is the difference between high and low risk strains of HPV. High risk HPV is oncogenic, meaning it has been associated with cancer, while low risk HPV is non-oncogenic. Most cases of HPV, especially in the developed world, are considered low risk. The most common strains of HPV vary by region, but types 6, 11, 16, and 18 are generally the most common.
Low Risk HPV
The most prevalent low risk strains of HPV are types 6 and 11. Low risk types of HPV are not associated with an increased risk of cancer compared to those without HPV.
The most common symptom of low risk HPV is anogenital warts (AGWs) which are common, usually benign, lesions. On males, AGWs are often found under the foreskin, on the shaft of the penis, and on the skin around the anus. On females, they are usually found on the vulva, around the opening of the vaginal canal, as well as around the anus. AGWs can spread from one area of the anogenital tract to another without new sexual contact. For example, warts can spread from the vulva to the skin around the anus without anal sexual contact. AGWs may resolve spontaneously. It is still important to see a doctor for AGWs in order to confirm they are in fact warts resulting from low risk HPV rather than something more malignant and to treat them to prevent spread.
Low risk HPV can also result in recurring papillomas (benign tumors, much like warts) in the respiratory tract, although it is somewhat rare. The most common location of these warts is in the voice box. This condition is known as Recurrent Respiratory Papillomatosis (RRP), and it is most common in young children and adults. Adults usually contract RRP from direct contact, while children often contract it during childbirth from a mother with genital warts. RRP is much more common in developing countries. There is no definitive cure for RRP, but laser therapy and surgery are the most common treatments. Cancerous and pre-cancerous outcomes are extremely rare in RRP.
High Risk HPV
High risk strains of HPV are those that are linked to cancer. The most prevalent strains are types 16 and 18. These two types alone are responsible for 70% of cervical cancers. High risk HPV is also associated with the vast majority of anal and oropharyngeal (back part of tongue) cancers. High risk HPV is not as common as low risk HPV, but it sill poses a substantial threat to public health.
Over 99% of cases of cervical cancer have been associated with HPV, and it is the 4th most common cancer in women worldwide. The mortality rate of cervical cancer is substantially higher in developing countries, where the rate of HPV infection is proportionally high. Since the introduction of the HPV vaccine, the rate of cervical cancer has dropped considerably. African Americans and Natives are substantially more likely to develop cervical cancer as a result of HPV, likely due to lack of access to method of prevention and early intervention.
The vast majority of anal cancer cases are also associated with HPV. Most cases are diagnosed in Europe and North America due to the lack of access to testing in other regions or the world. The risk of developing anal cancer is substantially higher in people living with HIV and people who have previously had other genital tract cancers. This is believed to be because people living with HIV or who have previously had cancer have suppressed immune systems that cannot attack abnormal cells before they develop into cancer.
Penile cancer is a less common result of HPV in the U.S. than it is in Europe, likely due to the fact that circumcision is more common in the U.S. Over 80% of cases of penile cancer have been associated with HPV.
Conclusion
HPV is an extremely common STD, and it can result in serious consequences which include a variety of cancers. However, only high risk strains of HPV are associated with these consequences. Most cases of HPV are considered low-risk, so they may not result in cancer, and their symptoms often resolve spontaneously. The best way to prevent the consequences of both low and high risk HPV is to get vaccinated against HPV. The CDC recommends the HPV vaccine be administered between the ages of 11 to 12 years old. The FDA has indicated that the vaccine may be administered between the ages of 9 to 45 years old, although it may not be as effective in older adults. It is recommended that adults aged 27 to 45 years old consult their doctor about the efficacy and benefits of the vaccine. The vaccine works best prior to HPV exposure. Other methods of prevention include regular condom use and circumcision.
For further information:
https://www.fda.gov/media/90070/download?attachment https://www.mayoclinic.org/diseases-conditions/hpv-infection/symptoms-causes/syc-20351596
Assessed and Endorsed by the MedReport Medical Review Board