Understanding HPV: Transmission, Cancer Risks, and Prevention

Human papillomavirus (HPV) is recognized as the most common sexually transmitted infection in the United States. While most infections are asymptomatic and resolve spontaneously, persistent infections with high-risk HPV types are the primary cause of cervical cancer and are linked to several other malignancies in both women and men.

HPV consists of a family of small, double-stranded DNA viruses that infect the epithelium. There are more than 200 distinct types of the virus, which are differentiated by their genomic sequence. These types are generally categorized by where they infect the body and their associated health risks.

Understanding HPV Types and Risks

Most HPV types infect the cutaneous epithelium, which typically results in common skin warts. Approximately 40 types infect the mucosal epithelium, and these are further categorized based on their association with cancer.

Sexually transmitted HPV types are divided into low-risk and high-risk groups. High-risk HPV types can lead to various forms of cancer. There are 12 identified high-risk types: HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59. Among these, HPV 16 and HPV 18 are responsible for the majority of HPV-related cancers.

Associated Cancers and Health Impacts

Persistent infection with high-risk HPV is the cause of cervical cancer. It is also associated with cancers of the vulva, vagina, mouth, throat, penis, and anus. In addition to cancer, HPV infections can lead to the development of anogenital warts and precancers.

The scale of the impact was significant in 2019, when HPV caused an estimated 620,000 cancer cases in women and 70,000 cancer cases in men.

Transmission and Prevention

HPV is spread through vaginal, anal, or oral sex. Because the virus affects the skin, genital area, and throat, condoms provide some protection but do not offer total prevention as they do not cover all of the genital skin.

Prevention strategies focus on vaccination and screening. Prophylactic vaccines can prevent the development of HPV-related cancers. In the United States, a quadrivalent vaccine was licensed in 2006, followed by a bivalent vaccine in 2009 and a 9-valent vaccine in 2014.

The vaccine does not contain live virus or DNA from the virus, meaning it cannot cause cancer or other HPV-related illnesses. It is used to prevent the development of cancers rather than to treat existing HPV infections or diseases.

The Role of Screening

Currently, cervical cancer is the only HPV-caused cancer for which screening tests are available. These tests are used to identify precancerous cell changes before they progress into cancer, allowing for treatment that can prevent the disease from developing.

Screening is considered an important part of routine health care for individuals who have a cervix. For most people, the body controls the HPV infection on its own, with 90% of cases resolving without intervention.