Anal-rectal cytology: a review

Area of Science:

• Oncology
• Cytopathology
• Public Health

Background:

• Anal squamous cell carcinoma, a human papilloma virus (HPV)-related cancer, shows increasing incidence, particularly in HIV-positive men who have sex with men (MSM).
• Precursor lesions, analogous to cervical squamous intraepithelial lesions, are detectable via anal-rectal cytology and biopsy, offering an opportunity for early intervention.

Purpose of the Study:

• To evaluate the utility of anal-rectal cytology screening programs for detecting and eradicating precursor lesions of anal cancer.
• To establish guidelines for specimen adequacy, collection methods, and diagnostic terminology in anal cytology.

Main Methods:

• Anal-rectal cytology specimens, preferably liquid-based, collected by healthcare professionals or patients.
• Requirement for a minimum of 2,000-3,000 nucleate squamous cells for adequate specimens.
• Application of the Bethesda System for Reporting Cervical Cytology (TBS 2001) diagnostic terminology.

Main Results:

• The sensitivity and specificity of a single anal-rectal cytology specimen are comparable to those of a single cervical cytology test.
• Cytological interpretations may not always perfectly correlate with the severity of the detected lesions.
• Referral for anoscopy is recommended for patients with atypical squamous cells of undetermined significance (ASC-US) or more severe findings.

Conclusions:

• Anal-rectal cytology screening is a viable strategy for identifying high-grade squamous intraepithelial lesions and preventing invasive anal cancer.
• Standardized methods and terminology, adapted from cervical cytology, are essential for reliable anal cytology interpretation.
• Close monitoring and follow-up, including anoscopy, are critical for managing abnormal anal cytology results and mitigating cancer risk.