Anal Precancer

What is anal pre-cancer or HSIL?

Anal precancer, otherwise known as, high-grade squamous intraepithelial lesions (HSIL), are abnormal cells found on the surface of the anus, or the bottom. These cells are considered precancerous and have the potential to develop into anal cancer if left untreated. Anal HSIL is often caused by persistent infection with human papillomavirus (HPV), particularly HPV types 16 and 18.

Risk factors for anal HSIL include smoking, HIV, having a weakened immune system due to a particular health condition or because you are on medication or treatment that suppresses your immune system, other genital cancers or pre-cancers.

Symptoms of anal HSIL

Many people with anal HSIL do not experience any symptoms. However, some individuals may notice:

  • Anal pain or discomfort
  • Anal itching
  • Blood from the bottom or blood in the poo
  • Pooing more often or less often than normal
  • Feeling or seeing lumps or growths around the bottom

It's important to note that these symptoms can also be caused by other conditions, so it's essential to see a healthcare provider for an accurate diagnosis.

Diagnosis

Anal HSIL is typically diagnosed through a combination of methods, including:

  • Physical examination: Your healthcare provider will look at your bottom and examine it with a gloved finger or small camera.
  • Anal pap smear: Like a pap smear for cervical cancer screening, an anal pap smear involves collecting cells with a small swab from the anus for examination under a microscope. This test can detect abnormal cells indicative of HSIL.
  • High resolution anoscopy (HRA): This procedure involves using a special magnifying instrument to examine the anus and identify any abnormal areas more clearly.

Treatment options

Treatment for anal pre-cancer aims to remove or destroy the abnormal cells to prevent the development of anal cancer. Treatment options may include:

  • Topical therapies: Medications such as imiquimod cream (Aldara) or 5-fluorouracil (5-FU or efudix) may be applied directly to the affected area to destroy abnormal cells.
  • Surgical procedures: Surgical interventions, such as excision or ablation, may be recommended to remove the abnormal tissue.
  • Monitoring: In some cases, especially for low-grade, less concerning lesions, close monitoring without immediate treatment may be appropriate.

The choice of treatment depends on factors such as the size and location of the lesions, as well as individual patient preferences and medical history.

Prevention

Reducing the risk of anal HSIL and anal cancer can be achieved through:

  • Human Papilloma Virus (HPV) Vaccination: Getting vaccinated against HPV can significantly reduce the risk of developing anal HSIL and related cancers.
  • Safe Sexual Practices: Practicing safe sex, including using condoms, can help prevent the transmission of HPV and other sexually transmitted infections.
  • Smoking Cessation: Smoking is a risk factor for persistent HPV infection and therefore anal HSIL.

Follow-up care

After treatment for anal HSIL, regular follow-up appointments are important to monitor in case the abnormal cells come back or become more serious with repeat anal pap smears or high-resolution anoscopy as part of ongoing surveillance.

Further information

  • Centres for Disease Control and Prevention (CDC)
  • National Institutes of Health (NIH)
  • Cancer Research UK

Contact us

Anal HSIL is a pre-cancerous condition that requires prompt diagnosis and appropriate management. By seeking medical attention, following recommended treatment, and adopting preventive measures, individuals with anal HSIL can reduce their risk of developing anal cancer and maintain overall health and wellbeing.

E: chelwest.anogenitaldysplasiaservice@nhs.net

References

1) https://www.cancerresearchuk.org/about-cancer/anal-cancer/stages-types/number-staging/stage-0-anal-intraepithelialneoplasia
2) Lupi, Micol, et al. "Anal cancer in high-risk women: the lost tribe." Cancers 15.1 (2022): 60.