ABSTRACT
Cancers of the anal canal occur in the distal portion of the lower gastrointestinal tract, immediately inferior to the rectum. The anal canal consists of three histological types of mucosa, which from proximal to distal are glandular, transitional, and squamous epithelium. Anal cancer is more common in females, typically accounting for 60"-65" of all anal cancers. The two most common symptoms of anal cancer are perianal pain and perirectal bleeding, which are frequently associated with anal fissures, hemorrhoids, and other benign conditions, complicating the diagnosis of early malignant disease within the anal canal. The gold standard investigation for diagnosing anal cancers is examination under anesthesia of the anal canal and rectum and tissue biopsy for histological confirmation of malignancy. CT scanning of the thorax, abdomen, and pelvis is performed for accurate clinical staging of disease. Intensity modulated radiotherapy (IMRT) is the radiation technique widely adopted to treat anal cancers.
