Human papillomavirus (HPV) is a sexually transmitted infection that can affect multiple body systems. HPV is extremely common and most sexually active individuals will be exposed to HPV at some point. There are over 100 different types of HPV and around 40 of those types affect the genital area. HPV infects epithelial cells and can cause warts or lesions on the skin and mucous membranes. The most common body systems affected by HPV include the reproductive system, respiratory system, and skin.
HPV and the Reproductive System
HPV is highly contagious and is passed through genital skin-to-skin contact. The virus initially infects and replicates in the basal epithelial cells of the skin or mucosa. HPV can infect the entire lower genital tract including the vagina, cervix, vulva, penis, scrotum, and anus. In some cases, HPV can also be transmitted through oral sex and infect the mouth and throat.
In women, HPV most commonly affects the cervix and can cause cellular changes that may progress to precancer or cancer. HPV infection is the leading cause of cervical cancer which is the 4th most common cancer in women worldwide. High-risk HPV types 16 and 18 are responsible for around 70% of cervical cancers. HPV-related precancers and cancers in women also include vaginal, vulvar, anal, and oropharyngeal cancers.
In men, HPV can infect the penis, scrotum, and anus leading to genital warts and precancerous lesions. Men are carriers of high-risk HPV types that can be transmitted to sexual partners and increase the risk of cervical cancer in women. Less commonly, HPV can cause cancers of the penis, anus, and oropharynx in men.
HPV-Related Conditions of the Reproductive System
Common HPV associated conditions of the reproductive system include:
- Genital warts (low-risk HPV types 6 and 11) – soft, skin-colored growths on the genitals
- Cervical cell changes/dysplasia – abnormal cells on the cervix that may progress to cancer (high-risk HPV types 16 and 18)
- Cervical cancer – cancer of the cervix uteri (opening of the uterus)
- Vaginal cancer
- Vulvar cancer
- Anal cancer
- Penile cancer
- Oropharyngeal cancer – cancer of the throat/tonsil area
HPV-associated cancers often take years or even decades to develop after initial HPV infection. The precancerous changes caused by HPV can be detected through regular cervical cancer screening with Pap smears and HPV testing. HPV vaccination is also recommended to prevent infection with the high-risk HPV strains that cause 70% of cervical and other anogenital cancers.
HPV and the Respiratory System
Although not as common as genital infection, HPV can be transmitted through oral sexual contact and infect the oropharynx (throat and tonsil area). Like other HPV-related cancers, cancer of the oropharynx is associated with high-risk HPV types 16 and 18. HPV-positive oropharyngeal cancer has been increasing steadily over the past few decades and now accounts for the majority of oropharyngeal cancers in the United States.
HPV is believed to gain access to the oropharyngeal mucosa through micro abrasions that occur during oral sex. The virus infects the basal epithelial cells of the oropharynx and disrupts the cell cycle, which can lead to DNA damage and cancer development over time. Males are at higher risk of HPV-related oropharyngeal cancer than females.
In addition to cancer, HPV can cause warts or papillomas to form in the larynx, trachea, bronchi, and lungs. These growths can obstruct breathing and cause other respiratory problems. However, HPV-related warts in the lower respiratory tract are relatively uncommon.
Signs and Symptoms of HPV-Related Oropharyngeal Cancer
- Persistent sore throat
- Hoarseness
- Difficulty swallowing
- Ear pain
- Swollen lymph nodes in neck
- Lump or mass in neck
HPV testing is now recommended along with visual oral cancer screening since oropharyngeal cancer linked to HPV has a better prognosis than non HPV-associated oral cancer. Vaccination against HPV may also reduce the future incidence of HPV-positive oropharyngeal cancers.
HPV and the Skin
Over 100 strains of HPV can infect various areas of the skin and mucous membranes. HPV affects the skin by causing common warts, plantar warts, flat warts, and palmar warts on the hands.
Warts are noncancerous skin growths caused by low-risk HPV types that infect the outer layers of skin. Common warts have a rough, bumpy texture and most often occur on hands and knees. Plantar warts affect the soles of the feet, while flat warts develop on the face, legs, or arms. Palmar warts are found on the palms of the hands.
Genital warts or venereal warts are also caused by HPV infection. These warts occur on the mucous membranes and skin of the genitals. Certain high-risk HPV types are more likely to cause precancerous lesions on genital skin.
In people with weakened immune systems, such as those living with HIV, HPV can disseminate to infect large areas of skin. This extensive HPV infection of the skin is uncommon in the general population.
Signs and Symptoms of HPV Skin Infections
- Common warts – rough, grayish bumps usually on hands and knees
- Plantar warts – hard growths with black pinpoints on soles of feet
- Flat warts – smooth, flat-topped lesions on face, chest, or limbs
- Palmar warts – fleshy, non-painful bumps on palms of hands
- Genital warts – soft, skin-colored bumps in genital area
There is no cure for HPV skin infections, but warts can be removed through cryotherapy, laser treatment, or medicated topical solutions. Skin lesions should be evaluated to exclude precancerous changes. As with other forms of HPV, vaccination can help prevent future HPV skin infections and warts.
HPV and the Immune System
While not a direct effect on the immune system itself, HPV takes advantage of a weakened immune system. Individuals who are immunocompromised are less able to clear HPV infections from the body and are at higher risk of more extensive HPV-related diseases.
People living with HIV/AIDS have a higher prevalence of HPV infections including genital warts, cervical cancer, and anal cancer. HPV-related cancers and lesions tend to be more aggressive in HIV-positive individuals. Transplant patients on immunosuppressant medication also have an increased risk of HPV infection.
By evading the immune defenses, HPV is able to persist in the epithelium and cause abnormal cell changes that gradually progress to cancer. Immunosuppression allows the virus to replicate unchecked. HPV takes 10-30 years to manifest as cancer in people with normal immunity.
Restoring immune function with antiretroviral drugs in HIV patients helps the body regain some control over HPV. But HIV patients should be monitored closely for signs of HPV-related cancers and receive regular cervical/anal cancer screening.
Prevention of HPV Infections
HPV is difficult to prevent completely because it is ubiquitous and transmitted by skin-to-skin contact. However, safer sex practices such as using condoms can reduce the risk of contracting HPV. HPV vaccination is also recommended for girls/boys age 11-12 to protect against the major cancer-causing HPV strains. The HPV vaccine is over 99% effective at preventing precancerous lesions when given prior to exposure to the virus.
HPV vaccination targets the HPV strains responsible for 70% of cervical cancers and 90% of genital warts. The vaccine won’t treat existing HPV infections but can prevent future infection by those strains. HPV vaccination may also help reduce rates of other HPV-related cancers.
Diagnosis of HPV
HPV testing is used to screen for high-risk HPV strains that can cause cellular changes leading to cancer. A sample of cells is collected from the cervix or oropharynx and tested for HPV DNA. A positive HPV test indicates infection with a cancer-associated strain but does not confirm precancer or cancer is present.
Further diagnostic evaluation with colposcopy and biopsy is recommended after a positive HPV test. HPV testing combined with a Pap smear is the preferred cervical cancer screening method for women age 30 and up. HPV DNA testing can also be done on tissue specimens from cervical, vaginal, vulvar, anal, and oropharyngeal cancers.
Treatment of HPV and Related Conditions
There is no cure for the HPV virus itself. However, HPV-related lesions and cancers can be treated.
Genital warts can be treated and removed through topical medications, cryotherapy, laser therapy, surgery, and other techniques. Pretreatment of warts with topical imiquimod may enhance laser removal. Getting rid of visible warts reduces symptoms but does not eliminate HPV infection.
Cervical precancerous lesions can be monitored with colposcopy and biopsy then removed using loop electrosurgical excision, cryotherapy, laser ablation, or conization. Cervical cancers are treated with surgery, chemotherapy, radiation, or combined approaches.
Likewise, surgical excision and chemoradiation are standard treatments for other HPV-associated cancers including oropharyngeal cancer. Immunotherapy drugs like pembrolizumab are sometimes used if tumors express PD-L1. The prognosis is better for HPV-positive oropharyngeal cancers versus non HPV-related oral cancers.
Prognosis and Prevention of HPV Cancers
Many low-risk HPV infections resolve spontaneously within 1-2 years. However, high-risk HPV infection persists longer and can progress to cancer over time if left untreated. Precancerous changes precede actual HPV-related cancers by 10-20 years in people with healthy immune function.
Catching and treating HPV-induced lesions at the earliest dysplasia stages before invasion prevents development of cancer. Hence, regular cervical and anal cancer screening is crucial for early identification. HPV vaccination protects against the HPV types responsible for most cervical and other anogenital cancers.
The overall 5-year survival rate for cervical cancer is around 65%, but prognosis is better when detected early at the localized precancerous stage. Oropharyngeal cancers related to HPV have better outcomes than non HPV-associated oral cancers. Taking preventive measures reduces the long-term cancer risks associated with HPV infection.
Conclusion
In summary, HPV is a sexually transmitted infection that predominantly affects the epithelial cells lining the reproductive tract, oropharynx, and skin surfaces. The virus can cause warts, precancerous lesions, and eventually cancer in infected areas over the span of years to decades if left undetected and untreated.
HPV impacts multiple body systems, but the reproductive and respiratory tracts are most commonly affected due to sexual transmission of the virus. Cervical, vulvar, vaginal, penile, anal, and oropharyngeal cancers are all associated with high-risk HPV types.
Cutaneous HPV types cause common warts, plantar warts, palmar warts, flat warts, and widespread skin infection in the context of immunosuppression. Weakened immunity allows greater HPV proliferation and reduces the body’s ability to clear infection.
By causing abnormal cellular changes, HPV disrupts the normal functioning of the reproductive, respiratory, and integumentary systems. Catching precancerous changes early and removing HPV-related lesions prevents progression to cancer. HPV vaccination provides the best protection against future infection and reduced cancer risk.