for Carcinoma of the Anal Canal A Randomized Controlled Trial

noses projected for the year 2008, ap-proximately 5070 will be new cases of anal canal carcinoma.1 Anal canal car-cinoma has a unique clinical biology that can be distinguished from all other gastrointestinal cancers. It is mostly a local-regional cancer, with a meta-static potential in only 15 % of pa-tients,2 and it is highly sensitive to con-current chemoradiation,3 resulting in a cure in 60 % of cases. The size of the primary tumor has a direct bearing on the cure rates,4-6 and the 5-year sur-vival rates decrease precipitously for tu-mors larger than 5 cm in diameter.7 Similarly, the presence of nodal metas-tases results in a reduction in the cure rate.4,8-10 In addition, with larger pri-mary cancers, the likelihood of lymph nodemetastases increases.11-14 Approxi-mately 25%of newly diagnosed anal ca-nal carcinomas are larger than 5 cm in diameter and clinically node-positive. It has been established that chemora-diationismoreeffectivetherapyforsmaller analcanalcarcinomasthanforlargerones. Thissuggests thatastrategythatcouldre-duce theburdenofcancer in theprimarySee also Patient Page. Author Affiliations are listed at the end of this article