Anal canal cancer

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While small tumours (<2 cm) arising in the anal canal may be amenable to local excision, most patients present with lesions of greater dimensions. Thanks to the pioneering work of Nigro, it is now widely accepted that the majority of cases can be cured by a combination of external-beam radiation therapy and chemotherapy with fluorouracil and mitomycin. Currently, the standard of care consists in the combination of radiation and chemotherapy, which has proven superior to radiotherapy alone in two randomised trials conducted in Europe _{[42, 43]}. In the EORTC trial, 110 patients with Stage II or III SCCA were randomised to receive either external-beam radiation (45 Gy over 5 weeks, with a 15 Gy boost) with concurrent chemotherapy (5-fluorouracil and mitomycin-C) or radiotherapy alone.  The dose of 5-FU was 750 mg/m2 on days 1–5 and 29–33; the dose of mitomycin was 15 mg/m2 on day 1. The chemoradiation protocol resulted in a higher remission rate (80% vs. 54%) and a 32% higher colostomy-free rate.

Following chemoradiation, patients should be examined at 3-months intervals, if possible under anaesthesia, and biopsy specimen taken of any induration or zone suspicious for recurrence.  The functional results are usually good, and most patients retain a functional anal sphincter, with no alteration in their lifestyle.

However, it is known that radiation negatively affects the internal sphincter function, with resulting faecal incontinence in a small percentage of cases _[44]. It is important to differentiate residual disease (positive biopsies less than 6 months after completion of chemoradiation) from tumour recurrence (complete response initially, with positive biopsies more than 6 months after cessation of treatment) _[45]. In most cases, recurrence occurs within 2 years of CRT. Patients with locally recurrent anal canal cancer should undergo an APR. It is estimated that, only 50% of patients who have locally recurrent SCCA following CRT will be cured with salvage APR.

CRT may be given safely at conventional doses in HIV-positive patients _[46]. However, it has been demonstrated that this subset of SCAA patients have a poor outcome, with response rate and 2-year colostomy-free survival rate of less than 50% _{[47, 48]}.  These data support the routine screening for anal intraepithelial lesions in HIV-positive patients _[49].

Anal margin cancer
Wide local excision is usually recommended for anal margin cancer, with excellent results. Epidermoid carcinomas of the anal margin rarely metastasise to visceral organs.  Recurrences may occur and are managed by re-excision in most cases. Combined chemoradiotherapy with 5-fluo-rouracile and mitomycin C remains an option in patients with locally advanced tumours (>5 cm).

As for most skin cancers, the prognosis is good with 5-year survival rates reportedly up to 90% _[41].

Correspondence:
Pascal Gervaz, MD
Clinique de Chirurgie Viscerale
Hopital Cantonal Universitaire de Geneve
Rue Micheli-du-Crest 24
CH-1211 Geneve
E-Mail:

RELATED STORIES:
Anal intraepithelial neoplasia (AIN) in the antiretroviral therapy era   Anorectal Cancer   Malignant tumors of the anal canal: the spectrum of disease, treatment, and outcomes   Carcinoma of the anus   Anal cancer: study   Carcinoma of the Anus   Epidermoid carcinoma of the anal canal   Anal Carcinoma

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