Anus & perianal area
Carcinoma
Carcinoma overview
Author: Raul S. Gonzalez, M.D.
Last author update: 30 March 2021
Last staff update: 21 November 2024 (update in progress)
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Anus [title] carcinoma "free full text"[sb]
Table of Contents
Definition / general | Essential features | Epidemiology | Pathophysiology | Clinical features | Diagnosis | Prognostic factors | Treatment | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Gonzalez RS. Carcinoma overview. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/anuscarcinomageneral.html. Accessed December 30th, 2024.
Definition / general
- Carcinoma arising in anus, usually of squamous origin
- WHO classification includes squamous cell carcinoma, verrucous carcinoma, undifferentiated carcinoma, adenocarcinoma, mucinous adenocarcinoma, neuroendocrine tumor and neuroendocrine carcinoma
- Per WHO: anal canal tumor "cannot be seen in its entirety, or at all, when gentle traction is placed on the buttocks" but perianal tumor "is found within a 5 cm radius of the anus and is seen completely when gentle traction is placed on the anus"
Essential features
- Most anal carcinomas are squamous, with HPV as a risk factor
- Most common in middle aged women
Epidemiology
- Uncommon (1 - 2% of GI tumors)
- More common in women (2 - 4:1); average age at diagnosis is early 60s
- Rising incidence in past 25 years (Oncologist 2007;12:524)
- American Cancer Society estimates for 2015: 7,270 cases and 1,010 deaths in the United States (American Cancer Society: Anal Cancer [Accessed 11 October 2017])
Pathophysiology
- Most anal squamous carcinomas are linked to infection with human papillomavirus 16 or 18 (Mod Pathol 1996;9:614, Mod Pathol 1989;2:439)
- HPV vaccination therefore may lead to decreased incidence (J Low Genit Tract Dis 2013;17:397)
- Other risk factors include HIV infection, smoking, male receptive anal intercourse (Ann Intern Med 2008;148:728, N Engl J Med 1987;317:973)
Clinical features
- Symptoms include rectal / anal bleeding, anal pain or itching, change in bowel habits, feeling of a mass at anal opening
Diagnosis
- Annual screening of at risk populations using anal Pap smear appears effective (JAMA 1999;281:1822)
Prognostic factors
- 5 year survival rate is 80 - 90% for T1 / T2 cancers, compared with 50% for T4 cancers (Int J Health Sci (Qassim) 2012;6:206)
- Lymph node involvement is a poor prognostic factor (Ann Surg Oncol 2007;14:478)
Treatment
- Surgery alone for small lesions; advanced tumors may also require chemoradiation (5-fluorouracil / mitomycin) (Curr Oncol Rep 2009;11:186)
Differential diagnosis
- Rectal carcinoma:
- Depending on subtype, may be difficult to distinguish from anal adenocarcinoma or anal squamous cell carcinoma
Board review style question #1
- What is the most common primary tumor of the anus?
- Adenocarcinoma
- Basal cell carcinoma
- Neuroendocrine carcinoma
- Squamous cell carcinoma
Board review style answer #1
Board review style question #2
- What screening method can be used for patients at high risk of anal carcinoma?
- Annual anal Pap smear
- Annual colonoscopy
- Annual CT scan
- Annual MRI scan
Board review style answer #2
