ABSTRACT
Anal cancer is relatively rare compared with colon and rectal cancer, but it is becoming more common, both absolutely and in relative terms: a generation ago, there were 100 cases of colorectal cancer for each anal cancer – that number has fallen to 27, while at the same time colorectal cancer has become more common. Anal cancer remains relatively much less common in Western countries than in several other locations, including parts of Brazil and India. Most tumors are epidermoid (including squamous cell, basaloid, and mucoepidermoid types); malignant melanoma is even more rare, and responds poorly to surgery and other modalities.
