The widely accepted treatment of most localized epidermoid, cloacogenic, or transitional cell carcinoma of the anal canal is:

D. Combined chemoradiation.

DISCUSSION: Tumors arising in the anal canal or in the transitional zone that have squamous, basaloid, cloacogenic, or mucoepidermoid epithelium are similar in their clinical presentation and response to treatment. Combined chemoradiation (the so-called Nigro protocol) promises to preserve continence, avoid colostomy, and offer a similar survival rate. Local excision is reserved for the few very small and superficial lesions. For most lesions, chemoradiation—external-beam radiation, 5-fluorouracil, and mitomycin C—is the treatment of choice.