Focal residual rectal glands can be seen in the center of the photomicrograph. (Source: Shutterstock)
Anal cancers are rare malignant tumours of the rectum and of the anal canal. The degree of malignancy depends on its location, size, depth, expansion and histologic composition. The carcinoma of the rectum is attributed to skin tumours, but has a better chance of cure because they usually are recognized at an early stage. The carcinoma of the anal canal, however, is often diagnosed late.
Various factors play a role in the development of anal cancer. For example, rectum cancer arises from precancerous lesions which are sometimes misinterpreted as eczema, and develops over many years. The cancer development can be promoted by certain virus types with a weakened immune system. Anal warts can also grow into an anal cancer. Immunodeficiency (e.g., AIDS), passive anal intercourse, and smoking, are risk factors.
Signs of an anal carcinoma can be blood coming from the anus and nodular indurations of the rectum. Cramping pain, irregular stools and involuntary bowel movement suggest an advanced stage of anal cancer, as well as enlarged rough inguinal lymph nodes. Inspection of the outer and inner anal region with the finger leads to the diagnosis which is secured by a tissue sample. Also instrumental examination is required for tumours in the anal canal.
For smaller, i.e. rather superficially located tumours, especially of the rectum and the lower anal canal, surgical treatment is the first option. Surgical treatment is also a first option with greater depth extension into the anal canal. At greater depth extension and/or localization of tumours in the upper anal canal, a combination of radiotherapy and chemotherapy takes place. Unfortunately, anal cancers infiltrate very early in the muscles of the sphincter, so when surgery is used, saving this muscle is usually not possible.
Anal Carcinoma of the lower anal canal and the rectum occur in men about three to four times as often as women, while anal cancers of the upper anal canal more frequently occur in women. Anal canal cancers occur predominantly from the age of 60. These cancers in an earlier age occur in immune deficiency (AIDS, blood cancer, immunocompromised organ transplanted patients).