Colon cancer
What is it?
Cancer of the edge of the anus and anal canal make up about 1% of all tumors of the digestive tract and about 2.5-5% of all colon tumors. The most common forms are squamous cell carcinoma, adenocarcinoma, and melanoma.
Causes and risk factors
Risk factors that can subsequently lead to anal canal cancer include:
- chronic papillomavirus infection (can lead to squamous cell carcinoma);
- HIV infection;
- infections due to squamous cell intraepithelial lesions;
- condylomas;
- pigmented nevi.
Anal canal cancer can also mimic or develop, although rarely, on very common benign growths such as hemorrhoids, prolapsed hemorrhoids, chronic anal fissures, or anal fistulas, which have been neglected for a long time, but which are nevertheless not therefore are precancerous conditions.
Which are the symptoms?
The clinical manifestations of anus tumors are often late, and patients often attribute pain and bleeding to more common anorectal conditions such as hemorrhoids or fissures. Other symptoms include anal itching, mucous-serous discharge from the anus, or fecal incontinence. Anal cancer may resemble hemorrhoids or anal fissures or may lead to a fistula in the perianal, vaginal, or vulvar area. Malignant melanoma of the anus resembles a pigmented nevus.
How is it diagnosed?
Diagnosis is made by a coloproctologist by examination of the perianal area, examination of 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 by exiting into it, and biopsy of the lesion site for histologic confirmation.
Endoanal ultrasound is the fundamental study to assess the extent of tumor invasion into the parietal region and connection with the sphincter apparatus. In fact, tumor progressive infiltration of the sphincter apparatus proved to be the most significant parameter in the occurrence of local recurrence and for patient survival rate. 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 treatable by the methods described. Computed tomography plays an important role in evaluating lymph node involvement and distant spread.
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How is it treated?
Lesions confined to the submucosal layer can only be adequately treated by local excision. In other cases, combined radiochemotherapy and, if necessary, interstitial brachytherapy by ultrasound-guided insertion of iridium-192 needles are used. These treatments give a high percentage of complete clinical remission. Surgical intervention (peritoneal-peritoneal amputation) is currently a salvage therapy only for those forms that have not responded to medical treatment.
Lack of response to the therapeutic procedure and tumor recurrence within 5 years can reach 30%.
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Where do we treat it?
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