ASCRS Ch19 — Anal Intraepithelial Neoplasia

Citation: Gaertner WB, Krane MK. "Anal Intraepithelial Neoplasia." In: Steele SR, et al. (eds.), The ASCRS Textbook of Colon and Rectal Surgery, 4th ed. Springer Nature Switzerland AG; 2022. pp. 343–354 (PDF pp. 350–362 of the combined textbook file). Source file: raw/ASCRS Textbook 4th Ed.pdf (full 1,198-page textbook; cite by page range within the single PDF). Ninth and final chapter of Part II ("Anorectal Disease") — Part III ("Malignant Disease") begins immediately after with ASCRS Ch20.

Type: Specialty textbook chapter (reference/background, not primary literature).

Scope

Nineteenth chapter of the sequential full-textbook ingest (see ASCRS Ch01 - Anatomy and Embryology for the ingest's scope/plan). Covers AIN as a single cohesive premalignant entity: nomenclature (LAST project two-tiered LSIL/HSIL system correlating with AIN-1 vs. AIN-2/3), epidemiology (HPV risk factors, high-risk subtypes 16/18/31/33/35/45, HPV vaccine impact), incidence/conversion-rate controversy, screening/surveillance (anal cytology technique, ANCHOR trial, immunosuppressed-population screening rationale), progression biology (extracted largely from cervical-cancer literature), diagnosis (cytology, biopsy, high-resolution anoscopy/HRA technique), treatment (expectant management, topical therapies — TCA, 5-FU, cidofovir, imiquimod — local ablative therapies — electrocautery, IRC — wide local excision, and a treatment-summary algorithm by AIN grade and immune status), and surveillance/prevention (recurrence rates, HPV vaccination efficacy data).

Key content

Filed as a single new condition page, Anal Intraepithelial Neoplasia — one cohesive premalignant entity, no split needed (unlike Ch12/13/16). Closes forward references flagged in three previously- ingested pages: Colorectal Anatomy & Embryology (anal-transition-zone HPV-dysplasia anatomy), Anorectal Sexually Transmitted Infections (HPV 16/18 oncogenic-subtype mention, HRA screening recommendation for high-risk MSM/HIV+ patients), and Pruritus Ani (Bowen's disease/Paget disease/ cloacogenic carcinoma named as refractory-pruritus differentials).

Limitations

• Textbook chapter, not primary literature; cited trial/cohort data (Giuliano quadrivalent-HPV- vaccine RCT, imiquimod/cidofovir/5-FU response-rate studies, Scholefield and Watson AIN-progression cohorts) are the chapter authors' synthesis, not independently re-verified.
• Explicitly flags the AIN-to-SCC conversion rate as controversial, with meaningfully different figures across study designs (9–13%/5yr in some prospective studies vs. 1-in-600-to-4000/yr in a large 2012 meta-analysis) — not reconciled by the chapter, reported as-is on the resulting page.
• The ANCHOR trial (treating HSIL vs. active surveillance in HIV-infected individuals) — directly relevant to the core clinical question of whether AIN treatment reduces anal cancer incidence — had not yet reported results at the time of this chapter's writing.
• Much of the AIN-to-SCC progression biology is explicitly extracted from the cervical cancer literature rather than anal-cancer-specific data, per the chapter's own acknowledgment.

Relevance

Nineteenth entry in the ASCRS ingest, and the last chapter of Part II ("Anorectal Disease"). Adds one new condition page and closes three previously-flagged forward references. Chapter 20 begins Part III ("Malignant Disease") with "Anal Cancer."