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HPV Associated with Cervical Cancer: Understanding the Link and Prevention

Human Papillomavirus (HPV) is a small double-stranded DNA virus, approximately 52-60 nm in size, with a genome of 7.9 kb. It primarily infects the epithelial cells of the anogenital region and oral mucosa, and is spread mostly through sexual contact. HPV can be categorized into two types: high-risk and low-risk. High-risk HPV types are directly associated with almost all cases of cervical cancer, as well as cancers affecting the vulva, vagina, penis, anus, rectum, and some head and neck cancers.

How Common Is HPV?

HPV is one of the most prevalent sexually transmitted infections (STIs) worldwide. According to the CDC, it has the highest prevalence and incidence among all STIs. The World Health Organization (WHO) reported that in 2019, HPV caused approximately 620,000 cancer cases in women and 70,000 cases in men. In 2022, around 660,000 new cases of cervical cancer were diagnosed, with about 350,000 women dying from this disease globally.

How Does HPV Cause Cervical Cancer?

HPV features a non-enveloped capsid made of proteins called capsomers. The virus enters the body through minor skin tears, attaching to host cells and entering through endocytosis (a process where the virus is absorbed into the cell). Inside the cell, HPV utilizes two types of genes: early genes, which assist in replication, and late genes, which are involved in forming new virus particles. While most HPV infections are harmless and are cleared by the immune system without symptoms, certain high-risk strains like HPV 16 and HPV 18 can persist and lead to cancer development. These high-risk strains produce two oncoproteins, E6 and E7, which interfere with the body’s natural cell cycle regulation and lead to uncontrolled cell growth:
  • E6 Protein: Binds to and degrades p53, a tumor-suppressor protein crucial for cell cycle regulation and DNA repair.
  • E7 Protein: Inactivates the retinoblastoma (Rb) protein, which normally prevents uncontrollable cell division.
When these proteins disrupt their targets, infected cells can multiply uncontrollably, forming precancerous lesions that may progress to invasive cervical cancer if left untreated.

Cervical Cancer: What You Need to Know

Cervical cancer is the fourth most common cancer in women worldwide, with nearly all cases linked to HPV infection. The cervix, the lower part of the uterus, is where cancer usually develops after prolonged HPV infection. There are two primary types of cervical cancer:
  • Squamous Cell Carcinoma (SCC): The most common type, originating from the squamous cells lining the cervix.
  • Adenocarcinoma (AC): Less common, developing from the glandular cells inside the cervical canal.
HPV types 16 and 18 are responsible for approximately 70% of cervical cancer cases. HPV integration into the host’s DNA disrupts normal cellular functions, leading to cancerous growth.

Prevention and Testing for HPV

Preventing HPV infection is crucial for reducing the risk of developing cervical cancer. Effective preventive measures include:
  • Get Vaccinated: The HPV vaccine is widely available and effective in preventing infections from high-risk HPV types.
  • Routine Pap Tests: Regular screenings can detect abnormal cervical cells before they develop into cancer.
  • Safe Sex Practices: Using condoms and limiting sexual partners can reduce the risk of HPV transmission.
  • Avoid Smoking: Smoking weakens the immune system, making it harder for the body to clear HPV infections.

Risk Factors for HPV and Cervical Cancer

Several factors increase the likelihood of HPV infection and cervical cancer development:
  • Multiple sexual partners
  • Early sexual activity
  • A weakened immune system
  • Smoking
  • Co-infection with other STIs

Conclusion

HPV is the leading cause of cervical cancer, but the good news is that it is preventable. By understanding the risks, getting vaccinated, and attending regular screenings, the burden of cervical cancer can be significantly reduced. Stay informed, practice safe behaviors, and consult your healthcare provider about the HPV vaccine to protect yourself and your loved ones.

References

  1. Kusakabe, M., Taguchi, A., Sone, K., Mori, M., & Osuga, Y. (2023). Carcinogenesis and Management of Human Papillomavirus-Associated Cervical Cancer. International Journal of Clinical Oncology, 28, 965-974.
  2. Molina, M. A., Steenbergen, R. D., Pump, A., Kenyon, A. N., & Melchers, W. J. (2024). HPV Integration and Cervical Cancer: A Failed Evolutionary Viral Trait. Trends in Molecular Medicine.
  3. PDB101: Molecule of the Month: Human Papillomavirus and Vaccines. RCSB: PDB-101. Retrieved May 14, 2018.
  4. Tolstov, Y., Hadaschik, B., Pahernik, S., Hohenfellner, M., & Duensing, S. (January 2014). Human Papillomaviruses in Urological Malignancies: A Critical Assessment. Urologic Oncology, 32(1), 46.e19–27.
  5. Gottschling, M., Stamatakis, A., Nindl, I., Stockfleth, E., Alonso, Á., & Bravo, I. G. (2007). Multiple Evolutionary Mechanisms Drive Papillomavirus Diversification. Molecular Biology and Evolution, 24(5), 1242–58.
  6. International Committee on Taxonomy of Viruses. (February 2019). Retrieved March 26, 2019.

Written By:    Haruna Mustapha   Research Scientist

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