Understanding HPV 16 and 18
HPV is short for human papillomavirus, a common sexually transmitted infection. Over 100 varieties of HPV exist, but types 16 and 18 cause a majority of HPV-related health issues. Keep reading to learn more about these high-risk strains.
Classifying HPV Varieties
Not all types of HPV act the same. HPV varieties are grouped into categories based on their tendency to cause cancer or genital warts.
"High-risk" HPV strains like types 16 and 18 significantly raise the chance of developing cervical, vaginal, vulvar, anal, penile, and oropharyngeal cancers. Other high-risk types include 31, 33, 45, 52, and 58.
"Low-risk" HPV types 6 and 11 cause 90% of all genital warts cases but aren't linked to cancers. Types 6 and 11 are still problematic though and require treatment.
HPV 16 and 18's Cancer Risks
Combined, HPV 16 and HPV 18 account for roughly 70% of all cervical cancer cases and a sizable fraction of other HPV-related cancers.
HPV 16 alone causes over half of cervical cancers. It also heightens the risk of vaginal, vulvar, anal, throat, and penile cancers in comparison to other high-risk HPV types.
Likewise, HPV 18 significantly raises cervical cancer risk. One study found women infected with HPV 18 were 3.3 times more likely to develop cervical cancer than those without it.
Transmission and Symptoms
HPV spreads mainly through sexual contact with an infected partner. Intercourse isn't required for transmission - other intimate contact spreads HPV too.
In 90% of cases, the immune system clears an HPV infection naturally within 2 years. But sometimes the virus persists, raising cancer risks dramatically later in life.
HPV usually doesn't trigger obvious symptoms, furthering its spread. Rarely, some people develop genital warts. Abnormal Pap test results may also indicate an HPV infection.
Reducing HPV 16/18 Cancer Risks
Once infected with a high-risk HPV strain, a person stays at increased risk for cancers. However, several key prevention and screening steps can greatly reduce HPV 16/18's cancer risks.
HPV Vaccination
Getting vaccinated against HPV as a preteen stops infection in its tracks for some strains. The Gardasil vaccine protects against infection from HPV types 16 and 18 (along with genital wart-causing types 6 and 11).
Clinical trials found Gardasil prevented 98% of cervical cell changes due to HPV 16/18. Experts endorse routine vaccination between ages 9-12 to promote immunity well before sexual activity starts.
Safe Sex Practices
Condoms reduce HPV transmission risk but don't fully eliminate it since skin not covered by the condom can still shed virus. Limiting sexual partners is another common sense way to reduce exposure.
Asking partners to get tested before intimacy - and sharing own results - allows each person to make informed decisions about STD risks.
Routine Pap and/or HPV testing enable early abnormal cell discovery so cancer doesn't develop. Although screening doesn't make up for vaccination or safe sex lapses, it serves as an essential safety net.
Current guidelines recommend Pap testing every 3 years for women ages 21-29. For those 30-65, co-testing with Pap plus HPV testing every 5 years is preferred.
Treatment Options for HPV 16 and 18
No approved medicines treat established HPV 16 or 18 infections directly. However, various treatments address cell changes and conditions these strains cause.
Cone Biopsy
When a Pap test detects abnormal cervical cells, a healthcare provider takes small tissue samples. If results show precancerous changes linked to HPV 16/18, surgery removes the transformation zone around the cervical opening.
LEEP
Loop electrosurgical excision procedure (LEEP) also treats precancerous cervical lesions using a thin electrified wire loop to painlessly remove abnormal cells.
Topical Treatments
Prescription creams like imiquimod (Aldara) stimulate immune cells near genital wart lesions to destroy HPV 6/11 infections. However, no topicals treat lesions due to HPV 16/18 specifically.
Oropharyngeal Cancer Treatment
When HPV 16/18 causes precancerous growths in the throat, typical treatments resemble head/neck cancer therapies like surgery, radiation, chemotherapy, or a combination.
The Global Impact of HPV 16 and 18
Beyond their sizable impact on cancer rates, HPV 16 and 18 also contribute greatly to cancer deaths worldwide. Understanding the global burden these strains exert underscores the importance of awareness and prevention.
HPV Attributable Cancers
The Population Attributable Fraction (PAF) indicates the proportion of cases likely caused by HPV 16/18 exposure globally. Research suggests HPV 16/18 could trigger:
- 78% of cervical cancers
- 93% of anal cancers
- 72% of vaginal cancers
- 63% of penile cancers
- 89% of vulvar cancers
In total, HPV 16 and 18 account for 5.2% of all human cancers worldwide.
Global Cancer Deaths
A 2020 study estimated 4.5% of annual cancer deaths worldwide resulted from HPV 16/18 exposure. Ranking eighth among cancer mortality causes, 317,000 deaths associate with HPV 16/18:
- 186,000 from cervical cancer
- 106,000 from other anogenital and oropharyngeal cancers
- 25,000 from other cancer types
These striking global statistics clearly demonstrate the preventable loss of life HPV 16/18 directly and indirectly trigger.
The Future of HPV 16/18 Prevention
Although HPV vaccination, screening, and cancer therapies continue advancing, significant work remains to reduce HPV 16 and 18's health burden.
Overcoming Access Barriers
Cost and logistics hamper vaccine availability globally, especially in remote and resource-strapped regions bearing the highest cervical cancer burdens. Improving affordability and distribution channels could prevent millions of cancers.
Novel Vaccine Formulations
Next generation HPV vaccines aiming for even broader type coverage and easier dosing schemes are underway. An oral vaccine alternative could boost vaccination rates in some demographics too.
Enhanced Screening Options
For unvaccinated older women, enhancements like combining Pap and HPV tests during scarce screening opportunities would maximize precancer detection. Self-collection protocols also show promise for underscreened groups.
Although work remains, the encouraging declines in HPV infection rates and precancer cases since vaccination introduction demonstrate prevention works when leveraged fully.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.
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