The anal canal is approximately an inch and a half long and contains a variety of cells. Squamous cells line the lower portion of the anus. These cells can sometimes develop genetic mutations that cause them to grow uncontrollably, leading to the development of cancer of the anus.
Types
Squamous cell carcinomas are the most common type of anal cancer, the American Society of Clinical Oncologists explains. Squamous cell carcinomas of the anus begin in the outer skin layer around the anus, though it can spread to other tissue layers, causing it to be termed invasive squamous cell carcinoma. Cloacogenic carcinomas, according to the American Cancer Society, are a subset of squamous cell carcinomas that begin in a region near the anus which is called the cloaca. These cells are treated similarly to regular squamous cell carcinomas.
Symptoms
Although many patients with anal squamous cell cancer do not have any symptoms, MayoClinic.com notes, there are some characteristic signs that may indicate that a patient is suffering from this rare form of cancer. Some patients with anal squamous cell cancer have itching in their anal region. Bleeding from the anus and anal pain are other symptoms. Some patients will have a noticeable mass or growth in the anus as well.
Risk Factors
There are a number of factors that can predispose a patient to developing squamous cell carcinoma of the anus, the American Society of Clinical Oncology indicates. HPV infection is a major risk factor for anal squamous cell carcinoma. Other risk factors include age, frequent anal irritation and cigarette smoking. Patients with an anal fistula, which is an abnormal connection between the anal canal and the anus can also predispose a person to developing anal cancer. People with weakened immune systems are also more likely to get this kind of cancer.
Diagnosis
Masses or growths in the anus can be detected during a physical exam, particularly if it includes a digital rectal exam, MayoClinic.com explains. A diagnosis of cancer typically hinges on taking a tissue sample from the mass and examining it under the microscope. One a diagnosis of anal squamous cell cancer has been confirmed, additional testing, including MRI, CT scans and x-rays, may help determine how far the cancer has spread.
Treatment
Squamous cell cancer of the anus is typically treated with a combination of chemotherapy and radiation therapy, the National Cancer Institute explains. The radiation treatment uses high energy x-rays to damage the cancerous squamous cells. Chemotherapy often involves the use of two different medications, called fluorouracil and mitomycin, which slow the cancerous cell growth. Severe cases may be treated with surgery, but it is no longer the treatment of choice for small anal tumors, the National Cancer Institute notes.
