What is the main risk factor for squamous cell (SCC) anal cancer?

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From the Guidelines

The main risk factor for espinocellular anal cancer is human papillomavirus (HPV) infection, particularly high-risk types such as HPV-16 and HPV-18. This association is strongly supported by recent evidence, including a 2023 study published in the Journal of the National Comprehensive Cancer Network, which found that high-risk HPV DNA was detected in 84% of anal cancer specimens 1. The virus is a major contributor to the development of anal cancer, and its presence is often linked to other risk factors such as receptive anal intercourse, sexually transmitted diseases, and immunosuppression.

Key Risk Factors

  • History of receptive anal intercourse or sexually transmitted disease
  • Immunocompromised state, such as HIV infection or solid organ transplantation
  • History of cervical, vulvar, or vaginal cancer
  • Smoking
  • Certain autoimmune disorders
  • Hematologic malignancies These factors can increase an individual's susceptibility to HPV infection and subsequent anal cancer development.

Prevention and Screening

HPV vaccination is a crucial preventive measure, especially for adolescents before they become sexually active, as it can significantly reduce the risk of developing anal cancer 1. Regular screening with anal cytology may also be beneficial for high-risk individuals to detect precancerous changes early.

From the Research

Main Risk Factor for Espinocellular Anal Cancer

The main risk factor for espinocellular anal cancer is:

  • Human papillomavirus (HPV) infection, specifically high-risk HPV types 2, 3, 4, 5, 6

HPV and Anal Cancer

  • HPV is the causal agent of cervical and other cancers, including anal cancer 2
  • High-risk HPV types are associated with almost 90% of cases of anal cancer 6
  • The prevalence of high-risk HPV in anal condylomas is high, especially in immunocompromised patients 3
  • HPV testing can be used to optimize the screening for anal cancer, especially in cases of normal and atypical squamous cells of undetermined significance cytology 6

Vaccine Efficacy

  • The HPV-16/18 AS04-adjuvanted vaccine has been shown to reduce HPV-16/18 infection and associated cervical endpoints in women, and may be effective against vulvar, oral, and anal HPV infection 2
  • The multisite woman-level vaccine efficacy was highest among "naïve" women, and also demonstrated among women with evidence of a pre-enrollment HPV16 or HPV18 infection 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Human papillomavirus and cervical cancer.

Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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