Abdominoperineal resection leading to permanent colostomy was previously thought to be required for all but small anal cancers below the dentate line, with approximately 70% of patients surviving 5 or more years in single institutions, but such surgery is no longer the treatment of choice.[2,3] Radiation therapy alone may lead to a 5-year survival rate in excess of 70%, though high doses (?60 Gy) may yield necrosis or fibrosis. Chemotherapy concurrent with lower-dose radiation therapy as evidenced in the RTOG-8314 trial, for example, has a 5-year survival rate in excess of 70% with low levels of acute and chronic morbidity, and few patients require surgery for dermal or sphincter toxic effects.[5,6,7,8,9,10] The optimal dose of radiation with concurrent chemotherapy to optimize local control and minimize sphincter toxic effects has been studied in the RTOG-9208 trial, for example, and appears to be in the 45 Gy to 60 Gy range.[11,12] Analysis of an intergroup trial that compared radiation therapy plus fluorouracil/mitomycin with radiation therapy plus fluorouracil alone in patients with anal cancer has shown improved results (lower colostomy rates and higher colostomy-free and disease-free survival) with the addition of mitomycin. Radiation with continuous infusion of fluorouracil plus cisplatin has been evaluated, as seen in the RTOG-9811 trial. Standard salvage therapy for those patients with either gross or microscopic residual disease following chemoradiation therapy has been abdominoperineal resection. Alternately, patients may be treated with additional salvage chemoradiation therapy in the form of fluorouracil, cisplatin, and a radiation boost to potentially avoid permanent colostomy.
Because of the small number of cases, information that can only come from patient participation in well-designed clinical trials is needed to improve the management of anal cancer. Patients with stages II, III, and IV disease should be considered candidates for clinical trials. Information about ongoing clinical trials is available from the NCI Web site.
In general, rectal carcinoids smaller than 1 cm can be safely removed by endoscopic excision. Excised specimens should be examined histologically to exclude muscularis invasion.[2,3,4,5]
Tumors measuring 1 cm to 2 cm should be investigated by transanal endosonography or magnetic resonance imaging. Absence of muscularis invasion or regional metastases may justify local excision. The outcome from treating a lesion between 1 cm and 2 cm is unclear. The metastatic risk is between 10% and 15%...
The tolerance of patients with human immunodeficiency virus (HIV) and anal carcinoma to standard fluorouracil/mitomycin chemoradiation is not well defined.[15,16] Patients with pretreatment CD4 counts of less than 200 may have increased acute and late toxic effects;[17,18] chemoradiation doses may require modification in this subset of patients.
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Fung CY, Willett CG, Efird JT, et al.: Chemoradiotherapy for anal carcinoma: what is the optimal radiation dose? Radiat Oncol Investig 2(3): 152-6, 1994.
John M, Pajak T, Flam M, et al.: Dose Escalation in Chemoradiation for Anal Cancer: Preliminary Results of RTOG 92-08 Cancer J Sci Am 2 (4): 205-11, 1996.
Flam M, John M, Pajak TF, et al.: Role of mitomycin in combination with fluorouracil and radiotherapy, and of salvage chemoradiation in the definitive nonsurgical treatment of epidermoid carcinoma of the anal canal: results of a phase III randomized intergroup study. J Clin Oncol 14 (9): 2527-39, 1996.
Rich TA, Ajani JA, Morrison WH, et al.: Chemoradiation therapy for anal cancer: radiation plus continuous infusion of 5-fluorouracil with or without cisplatin. Radiother Oncol 27 (3): 209-15, 1993.
Holland JM, Swift PS: Tolerance of patients with human immunodeficiency virus and anal carcinoma to treatment with combined chemotherapy and radiation therapy. Radiology 193 (1): 251-4, 1994.
Peddada AV, Smith DE, Rao AR, et al.: Chemotherapy and low-dose radiotherapy in the treatment of HIV-infected patients with carcinoma of the anal canal. Int J Radiat Oncol Biol Phys 37 (5): 1101-5, 1997.
Hoffman R, Welton ML, Klencke B, et al.: The significance of pretreatment CD4 count on the outcome and treatment tolerance of HIV-positive patients with anal cancer. Int J Radiat Oncol Biol Phys 44 (1): 127-31, 1999.
Place RJ, Gregorcyk SG, Huber PJ, et al.: Outcome analysis of HIV-positive patients with anal squamous cell carcinoma. Dis Colon Rectum 44 (4): 506-12, 2001.