anal cancer
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Etiology
- papillomavirus[4]
- Crohn's disease with perianal disease[4]
Epidemiology
- approximately 4% of lower GI tract cancers[1]
Pathology
- squamous carcinomas most common
- cloacogenic carcinoma
- 2-3% of anorectal carcinomas
- originates from persistent remnant of the cloacal membrane[2]
- adenocarcinoma
- melanoma
Clinical manifestations
- perirectal lesion or mass lesion
- variable appearance of lesion
- lesion may ulcerate[4]
- lesion may obstruct anal canal
- lesion may appear as non-protruding polyp
- lesion may appear as flat growth in anal canal[4]
- variable appearance of lesion
- rectal bleeding
- anal discomfort or pain, pruritus ani
- 25% of patients without anorectal symptoms[4]
Management
- chemotherapy plus radiation therapy for stages 1, 2 or 3[4]
- 5-fluorouracil plus mitomycin[3]
- 5-fluorouracil plus cisplatin with similar outcomes & toxicity, but administration is more difficult
- no benefit of adjuvant cisplatin[3]
- at least 4500 cGy of radiation[3]
- a boost of 1500-2000 cGy may be appropriate especially if chemotherapy is not possible[3]
- 5-fluorouracil plus mitomycin[3]
- 26 weeks is optimal for evaluating complete response
- anal tumors may continue to regress for 6-12 months following radiation therapy[4]
- relapse occurs in ~10%
- generally local or regional rather than metastatic
- consider surgical resection as salvage therapy
- surgical resection is generally avoided because it removes anal sphincter muscles necesitating a permanent colostomy[4]
More general terms
More specific terms
Additional terms
References
- ↑ 1.0 1.1 http://www.cancer.gov/cancertopics/types/anal
- ↑ 2.0 2.1 Sink JD, Kramer SA, Copeland DD, Seigler HF. Cloacogenic carcinoma. Ann Surg. 1978 July; 188(1): 53-59. PMID: https://www.ncbi.nlm.nih.gov/pubmed/666378
- ↑ 3.0 3.1 3.2 3.3 3.4 Anello J, Feinberg B, Heinegg J, Lindsey R, Wojdylo C, Wong O. Medcsape Oncology. August 2014 Guideline on Anal Cancer from the European Society for Medical Oncology, the European Society of Surgical Oncology and the the European Society of Radiotherapy and Oncology http://reference.medscape.com/features/slideshow/guidelines-review/august2014
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Medical Knowledge Self Assessment Program (MKSAP) 17, 18, 19. American College of Physicians, Philadelphia 2015, 2018, 2021.