Anal cancer

• • Relatively rare cancer of the GI tract
  • Majority are squamous cell carcinomas, arising from below the dentate line
  • The remainder are adenocarcinomas arising from the upper anal canal epithelium
• A precancerous condition called anal intraepithelial neoplasia may precede the development of invasive squamous anal carcinoma

  • Affect either the perianal skin or anal canal
  • Strongly linked to infection with HPV
  • High grade will need treatment - laser ablation, surgery and creams
• Risk factors:

  • HPV infection (accounts for 80-90% cases)
  • HIV infection
  • Increasing age
  • Smoking
  • Immunosuppression
  • Crohn's disease
• Clinical features:

  • Rectal pain
  • Rectal bleeding
  • Anal discharge
  • Pruritus
  • Palpable mass
  • If sphincters involved - incontinence and tenesmus
  • Mass felt on PR
  • Inguinal lymph nodes should be examined for any lymphadenopathy
• Initial investigations:

  • Protoscopy to better visualise anal canal
  • All patients with suspected anal cancer should then undergo examination under anaesthetic - biopsy
  • In women a smear test should also be undertaken
  • Consider HIV test for those with risk factors
• Once the diagnose has been confirmed by biopsy, further staging investigations are required:

  • Ultrasound-guided Fine Needle Aspiration (FNA) of any palpable inguinal lymph nodes
  • CT scan of chest-abdomen-pelvis for evidence of metastases
  • MRI pelvis to assess the extent of local invasion
• Management:

  • MDT
  • Chemo-radiotherapy often first choice treatment
  • Surgical for advanced disease - abdominoperineal resection (Surgery to remove the anus, the rectum, and part of the sigmoid colon through an incision made in the abdomen)