Uncommon cancer of anal canal and perianal skin, strongly associated with human papilloma virus
Similar risk factors to genital cancers
Majority are squamous cell carcinoma (adenocarcinoma rare)
Regional nodal metastases common
Distant metastases uncommon, usually liver if present
Above dentate line (upper 2/3 of anal canal)
Columnar epithelium
Adenocarcinomas (rare)
Treated similarly to rectal adenocarcinomas
Supplied by superior rectal artery
Drained by portal venous circulation
Lymphatic drainage to perirectal and paravertebral lymph nodes
Below dentate line (lower 1/3 of anal canal)
Stratified squamous epithelium
Squamous cell carcinomas
Supplied by inferior rectal artery
Drained by systemic circulation
Lymphatic drainage to inguinal and femoral lymph nodes
Perianal skin cancers
Involve anal margin or perianal skin
Most commonly squamous cell carcinoma
Often treated similarly to squamous cell carcinoma of anus (chemoradiotherapy), as it is difficult to delineate anal margin vs. skin
IMAGING
F-18 FDG PET/CT
CT
MR
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Ladbury C et al: Anal cancer in the era of dose painted intensity modulated radiation therapy: Implications for regional nodal therapy. Semin Radiat Oncol. 29(2):137-43, 2019
Ciombor KK et al: Diagnosis and diagnostic imaging of anal canal cancer. Surg Oncol Clin N Am. 26(1):45-55, 2017
Houard C et al: Role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography in post-treatment evaluation of anal carcinoma. J Nucl Med. 58(9):1414-20, 2017
Jones M et al: The role of FDG-PET in the initial staging and response assessment of anal cancer: A systematic review and meta-analysis. Ann Surg Oncol. 22(11):3574-81, 2015
Matalon SA et al: Anorectal cancer: critical anatomic and staging distinctions that affect use of radiation therapy. Radiographics. 35(7):2090-107, 2015
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KEY FACTS
Terminology
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TERMINOLOGY
Definitions
Anal carcinoma
Uncommon cancer of anal canal and perianal skin, strongly associated with human papilloma virus
Similar risk factors to genital cancers
Majority are squamous cell carcinoma (adenocarcinoma rare)
Regional nodal metastases common
Distant metastases uncommon, usually liver if present
Above dentate line (upper 2/3 of anal canal)
Columnar epithelium
Adenocarcinomas (rare)
Treated similarly to rectal adenocarcinomas
Supplied by superior rectal artery
Drained by portal venous circulation
Lymphatic drainage to perirectal and paravertebral lymph nodes
Below dentate line (lower 1/3 of anal canal)
Stratified squamous epithelium
Squamous cell carcinomas
Supplied by inferior rectal artery
Drained by systemic circulation
Lymphatic drainage to inguinal and femoral lymph nodes
Perianal skin cancers
Involve anal margin or perianal skin
Most commonly squamous cell carcinoma
Often treated similarly to squamous cell carcinoma of anus (chemoradiotherapy), as it is difficult to delineate anal margin vs. skin
IMAGING
F-18 FDG PET/CT
CT
MR
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Ladbury C et al: Anal cancer in the era of dose painted intensity modulated radiation therapy: Implications for regional nodal therapy. Semin Radiat Oncol. 29(2):137-43, 2019
Ciombor KK et al: Diagnosis and diagnostic imaging of anal canal cancer. Surg Oncol Clin N Am. 26(1):45-55, 2017
Houard C et al: Role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography in post-treatment evaluation of anal carcinoma. J Nucl Med. 58(9):1414-20, 2017
Jones M et al: The role of FDG-PET in the initial staging and response assessment of anal cancer: A systematic review and meta-analysis. Ann Surg Oncol. 22(11):3574-81, 2015
Matalon SA et al: Anorectal cancer: critical anatomic and staging distinctions that affect use of radiation therapy. Radiographics. 35(7):2090-107, 2015
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