How can I prevent anal cancer?

Anal cancer is an uncommon cancer, and the risk of developing anal cancer is quite low. Avoidance of risk factors for anal cancer, however, will reduce the risk of development of anal cancer even further. By far, the most important factor in developing anal cancer is infection with HPV. Recently, Gardasil, a vaccine directed against HPV, has been developed. This vaccination is currently recommended only for girls and young women for prevention of cervical cancer. Vaccination against HPV would certainly be expected to reduce the incidence of anal cancer in both men and women, but, to date, no studies have been published confirming this. The vaccine has not been studied in boys and men, but data on this topic will likely be available in the future. A number of studies examining the role of HPV vaccines and anal cancer are currently under development.
Avoiding smoking and unsafe sexual practices can reduce the risk of anal cancer. In patients who are known have anal dysplasia, careful surveillance can result in early detection of anal cancer, and a higher rate of cure with treatment., Removal of areas of anal dysplasia is usually unsuccessful, however. The rate of recurrence of anal dysplasia after surgical or laser removal is very high. This is likely due to the fact that even if areas of dysplasia are removed, the patient remains infected with HPV, which can cause the development of additional areas of anal dysplasia.

What are the signs of anal cancer?
The most common initial symptom of anal cancer is rectal bleeding, which occurs in about half of patients with new anal cancers. Pain is somewhat less common, seen in about 30% of patients with new anal cancers; however, it can be quite severe. Occasionally, patients have the sensation of having a mass in the anus and may experience itching or anal discharge. In certain patients, these symptoms may be associated with the presence of warts in the anal region. Rarely, in advanced cases, anal cancers can disrupt the function of the anal muscles, resulting in loss of control of bowel movements. In general, these symptoms are vague and non-specific. As a result, in one-half to two-thirds of patients with anal cancer, a delay of up to 6 months occurs between the time when symptoms start and when a diagnosis is made.

How is anal cancer diagnosed?
When anal cancer is suspected, the physician should perform a thorough history and physical examination. The physical exam should consist of a digital rectal examination (DRE) as well as visualization of the anal canal using an anoscope or bronchoscope (a long, thin instrument that is inserted into the anus to allow the physician to see the inside of the anus and rectum). Ultimately, anal cancer can only be diagnosed with a biopsy. To perform a biopsy, the physician uses a needle or a small pair of scissors or clamps to remove a piece of the tumor. It is common for there to be some mild bleeding after a biopsy is taken, and this bleeding can last for a few days after the procedure. The tissue is then sent to a pathologist who looks at the tissue underneath a microscope to determine whether the tumor is cancerous or not. Because a number of benign tumors and lesions can resemble anal cancer on physical examination, a biopsy should always be performed before initiating treatment for anal cancer.
How is anal cancer staged?
Once a diagnosis of anal cancer is made, additional test should be ordered to determine the extent of the disease. A CT (CAT) scan or MRI of the abdomen and pelvis should be performed to look for abnormally enlarged lymph nodes, which can result from spread of the cancer, and to examine the liver for metastatic disease. A chest x-ray is often performed to look for spread of the cancer to the lungs. In some cases, an ultrasound of the tumor using a probe that is inserted into the anus can be used to determine the amount of invasion of the tumor into the surrounding tissues.
Anal cancer is most commonly staged using the TNM staging system which is determined by the American Joint Committee on Cancer. The "T stage" represents the extent of the primary tumor itself. The "N stage" represents the degree of involvement of the lymph nodes. The "M stage" represents whether or not there is spread of the cancer to distant parts of the body. These are scored as follows:

T Stage
Tis: Carcinoma in situ
T0: No evidence of primary tumor
T1: Tumor 2 cm or less in greatest dimension
T2: Tumor is greater than2 cm but less than 5 cm in greatest dimension
T3: Tumor is greater than5 cm in greatest dimension
T4: Tumor of any size that invades adjacent organs including the vagina, urethra, or bladder. Tumors that invade the anal sphincter only do not qualify as T4 tumors

N Stage
N0: No evidence of spread to the lymph node
N1: Spread of cancer to the lymph nodes directly adjacent to the rectum (perirectal lymph nodes)
N2: Spread of the cancer to lymph nodes of the inguinal or internal iliac lymph node chains on one side only.
N3: Spread of the cancer to lymph nodes of the inguinal or internal iliac lymph node chains on both sides OR cancer involvement of both the perirectal lymph nodes and the inguinal lymph nodes

M Stage
M0: No evidence of distant spread of the cancer
M1: Evidence of distant spread of the cancer to other organs, or to lymph node chains other than the ones lists under "N stage"

The stage of the cancer is reported by stating the stage of the T, the N, and the M. For example, a patient with a 4 cm tumor that had spread to perirectal lymph nodes, but did not invade into adjacent organs or spread to any other lymph nodes would be classified as T2N1M0. The staging can be further condensed into a stage group, which takes the various combinations of TNM and places them into groups designated stage 0-IV. While there is a system for stage grouping of anal cancers, these tumors are more commonly referred to by their direct TNM stage.
Although this system of cancer staging is quite complicated, it is designed to help physicians describe the extent of the cancer, and therefore, helps to direct what type of treatment is given.