Anorectal: Anal Cancer

Anal Intraepithelial Neoplasia (AIN)

Basics

Grading

  • Historical Grading:
    • AIN I – Low-Grade
    • AIN II – Moderate-Grade
    • AIN III – High-Grade or SCC In Situ
  • Modern Grading:
    • Low-Grade Squamous Intraepithelial Lesion (LSIL) – AIN I
      • Replacement of Lower-Third of Epithelium by Abnormal Cells
    • High-Grade Squamous Intraepithelial Lesion (HSIL) – AIN II/III
      • Replacement of Upper/Middle-Thirds of Epithelium by Abnormal Cells

Treatment

  • LSIL: Observation
    • Surveillance Every 3-6 Months
    • Consider High Resolution Anoscopy (HRA) to Surveil
  • HSIL: Topical Therapy & Consider Ablation
    • Topical Tx: Imiquimod, 5-Fluorouracil (5-FU) or Trichloroacetic Acid (TCA)
    • Ablation Tx: Radiofrequency Ablation (RFA) or Electrocautery

Histology: (A) Normal, (B) LSIL, (C) HSIL 1

Anal Canal Cancer

TNM Staging

  • TNM
  T N M
1 ≤ 2 cm Positive LN Positive Mets
2 > 2 cm
3 > 5 cm
4 Invades Adjacent Organs
  • Staging
  T N M
I   T1 N0 M0
II A T2 N0 M0
B T3 N0 M0
III A T1-2 N1 M0
B T4 N0 M0
C T3-4 N1 M0
IV   Any T Any N M1

Squamous Cell Carcinoma (SCC)

  • Most Common Anal Canal Cancer (85%)
  • Tx: Nigro Protocol
    • Nigro Protocol: Chemo-XRT with 5-FU & Mitomycin (MMC)
    • 80-90% Success
    • Reassess at 8-12 Weeks & Then Every 6-8 Weeks Until Resolution
    • If Recurs or Fails After 6 Months: APR
      • First Bx to Confirm Dx
    • May Consider WLE with 1 cm Margin if < 2 cm

Adenocarcinoma

  • 10% of Anal Canal Cancers
  • Often Difficult to Differentiate from Low Rectal Tumors
  • Tx: WLE or APR

Basal Cell Carcinoma (BCC)

  • All Epidermoid Cancers Behave Similarly
  • Tx: Similar to SCC

Melanoma

  • Often Mistaken for a Thrombosed Hemorrhoid
  • Poor Prognosis (Median Survival < 2 Years)
  • Tx: WLE
    • No SLNB Needed
    • May Require APR if Extensive Sphincter Involvement

Other Tumors

Anal SCC 2

Anal Adenocarcinoma 3

APR 4

Anal Margin (Perianal) Cancer

Squamous Cell Carcinoma (SCC)

  • Staging Same as Anal Canal SCC
  • Tx: WLE or Chemo-XRT
    • Wide Local Excision (WLE):
      • Criteria: T1 (≤ 2 cm) & Does Not Involve the Sphincter
        • Possibly T2 (< 5 cm) As Well
      • Margins: 1 cm
    • If Criteria Not Met: Chemo-XRT

Basal Cell Carcinoma (BCC)

Perianal Paget’s Disease (PPD)

  • Intraepithelial Adenocarcinoma of the Anal Margin
  • May Be Primary from the Apocrine Glands or Secondary
    • 50% Have Synchronous Visceral Carcinomas
  • Sx: Severe Intractable Pruritis & Erythematous Eczematoid Rash
  • Workup Requires Complete Colonoscopy
  • Tx: WLE (1 cm Margin)
    • May Require APR if Locally Invasive

Perianal Paget Disease 5

References

  1. López-Morales D, Reyes-Leyva J, Santos-López G, Zenteno E, Vallejo-Ruiz V. Increased expression of sialic acid in cervical biopsies with squamous intraepithelial lesions. Diagn Pathol. 2010 Nov 22;5:74. (License: CC BY-2.0)
  2. Wollina U, Koch A, Heinig B, Kittner T, Nowak A. Acne inversa (Hidradenitis suppurativa): A review with a focus on pathogenesis and treatment. Indian Dermatol Online J. 2013 Jan;4(1):2-11. (License: CC BY-NC-SA-3.0)
  3. Matsunaga M, Miwa K, Oka Y, Nagasu S, Sakaue T, Fukahori M, Ushijima T, Akagi Y. mFOLFOX6 Chemotherapy after Resection of Anal Canal Mucinous Adenocarcinoma. Case Rep Oncol. 2016 Apr 29;9(1):280-4.(License: CC BY-NC-4.0)
  4. Terrone DG, Lepanto L, Billiard JS, Olivié D, Murphy-Lavallée J, Vandenbroucke F, Tang A. A primer to common major gastrointestinal post-surgical anatomy on CT-a pictorial review. Insights Imaging. 2011 Dec;2(6):631-638. (License: CC BY-2.0)
  5. Clark ME, Schlussel AT, Gagliano RA Jr. Management of Adenocarcinoma in the Setting of Recently Operated Perianal Paget’s Disease. Case Rep Surg. 2013;2013:510813.(License: CC BY-3.0)