Causes and risk factors
Risk factors that can subsequently lead to the formation of a tumor of the anal canal are:
- сhronic papillomavirus infection (can lead to squamous cell carcinoma);
- HIV infection;
- infection with lesions of the squamous intraepithelium;
- pigmented moles.
Anal canal cancer can also mimic or develop, though rarely, on very common benign growths such as mariska, prolapsed hemorrhoids, chronic anal fissure, or anal fistula, which have long been overlooked but are not precancerous conditions.
Which are the symptoms?
Clinical manifestations of anus tumors are often late, and patients often attribute pain and bleeding to more common anorectal diseases, such as hemorrhoids or erysipelas. Other symptoms include anal itching, mucous anal discharge, or fecal incontinence. Anal canal cancer can resemble hemorrhoids or anal fissures, or can lead to a fistula in the perianal, vulvar, or vaginal area. Malignant melanoma of the anus looks like a pigmented mole.
How is it diagnosed?
Diagnosis is made by a coloproctologist by examining the perianal area, as well as the anus and rectum to evaluate the size, location, and relative fixation of the tumor, anoscopy and rectosigmoidoscopy since rectal cancer can affect the anal canal, and biopsy of the lesion for histologic confirmation.
Endoanal ultrasound is the basic study to assess the degree of invasion of the parietal area by a tumor and the relationship with the sphincter apparatus. In fact, it has been shown that progressive infiltration of the sphincter apparatus by the tumor is the most significant parameter for local recurrence and patient survival. Endoanal ultrasound also plays an important role in post-therapy follow-up to detect recurrence before it becomes clinically evident, and thus at a stage still amenable to the treatments described. Computed tomography plays an important role in assessing lymph node involvement and distant spread.
How is it treated?
Lesions confined to the submucosal layer can be adequately treated only by local excision. In other cases, combined radiochemotherapy and possibly interstitial brachytherapy using ultrasound infusion of iridium-192 needles are used. These treatments result in a high percentage of complete clinical remission. Surgical intervention (abdomino-perineal amputation) is currently a lifesaving therapy only for those forms that have not responded to drug therapy.
Failure to respond to treatment therapy and tumor recurrence within 5 years can be as high as 30%.