Cancer describes a set of diseases in which normal cells in the body lose their ability to control their growth. As cancers grow, they may invade the tissues around them (local invasion) or spread to other locations in the body where they may implant and grow (metastases).
The anus or anal canal is the short passage through which stool or feces passes to exit the body at the time of a bowel movement.
Anal cancer arises from the cells around or just inside the anal opening. Anal cancer is often a type of cancer called squamous cell carcinoma. Other rare types of cancer may also occur in the anal canal, and these require consultation with your physician or surgeon to determine the appropriate evaluation and treatment.
Cells that are becoming malignant or “premalignant” but have not invaded deeper into the skin are often referred to as “high grade anal intraepithelial neoplasia” or HGAIN. While this condition is likely a precursor to anal cancer, this is not anal cancer and is treated differently than anal cancer. Your physician or colon and rectal surgeon can help clarify the differences.
How common is anal cancer?
There are almost 6,000 new cases of anal cancer being diagnosed each year in the U.S., accounting for about 1-2% of all intestinal cancers. Approximately one in 600 people will develop anal cancer in their lifetime (as compared to 1 in 20 people who will develop colorectal cancer). Unlike some cancers, the numbers of patients that develop anal cancer each year is slowly increasing.
Who is at risk?
A risk factor is something that increases a person’s chance of getting a disease. Anal cancer is commonly associated with an infection by the human papilloma virus (HPV). HPV can also cause warts in and around the anus or genitals in both men and women, but warts do not have to be present for anal cancer to develop. A history of other HPV-related cancers, especially cervical cancer, can put you at increased risk for anal cancer.
Additional risk factors for anal cancer include:
- Age (over age 55).
- Anal sex
- Sexually transmitted diseases
- Mltiple sex partners
- Weakened immune system (chemotherapy, transplant recipients, patients with HIV).
- Chronic local inflammation (long-standing anal fistulas or open wounds in the anal area)
- Pelvic radiation
Can anal cancer be prevented?
Few cancers can be totally prevented, but the risk of developing anal cancer may be decrease9 by avoiding the risk factors listed above and by getting regular checkups. Using condoms may reduce, but not eliminate, the risk of HPV infection. Vaccines against HPV infection have also been shown to decrease the risk of developing anal cancer (in men and women).
People who are at increased risk for anal cancer should talk to their doctors about consideration of anal cancer screening (much like the Pap tests women undergo· for cervical cancer screening). Early identification and treatment of premalignant areas in the anus may also prevent the development of anal cancer.
What are the symptoms of anal cancer?
Many cases of anal cancer can be found early because they form in a location that the doctor can see and reach easily. Anal cancers often cause symptoms such as:
- Rectal or anal bleeding
- A lump or mass at the anal opening
- Persistent or recurring pain or itching in the anal area
- Change in bowel habits (having more or fewer bowel movements) or increased straining during a bowel movement
- Narrowing of the stools
- Discharge or drainage (mucous or pus) from the anus
- Swollen lymph nodes (glands) in the anal or groin areas.
These symptoms can also be caused by less serious conditions, such as hemorrhoids, but you should never assume this. If you have any of these symptoms, see your doctor or colon and rectal surgeon.
How is anal cancer diagnosed?
Anal cancer is usually found on examination of the anus because of the presence of symptoms like those listed above, but may be found incidentally on yearly physical exams (rectal exam for prostate check or at the time of a pelvic exam) or on screening tests such as those recommended for preventing or diagnosing colorectal cancer. Anoscopy, or exam of the anus with a small lighted scope, may be performed to assess any abnormal findings. If an abnormal area in the anus is identified, a biopsy will be performed to determine the diagnosis. If the diagnosis of anal cancer is confirmed, additional tests to determine the extent of the cancer may be recommended.
How are anal cancers treated?
Treatment for most cases of anal cancer is very effective in curing the cancer. There are 3 basic types of treatment used for anal cancer:
- An operation to remove the cancer
- Radiation therapy – high-dose X-rays to kill cancer cells
- Giving drugs to kill cancer cells
Combination therapy with radiation and chemotherapy is now considered the standard treatment for most anal cancers. Occasionally a very small or early tumor may be removed surgically (“local excision”) without the need for further treatment. At times, more major surgery to remove the anal cancer is needed, and this requires the creation of a colostomy where the bowel is brought out to the skin on the belly wall where a bag is then attached to collect the fecal matter.
Will I need a colostomy?
The majority of patients treated for anal cancer will not need a colostomy. However, if the tumor does not respond completely to therapy, if it recurs after treatment, or if it is an unusual type of anal cancer, removal of the rectum and anus and creation of a permanent colostomy may be necessary.
What happens after treatment for anal cancer?
Most anal cancers are cured with combination therapy, and some cancers that recur despite treatment may be successfully treated with surgery if they are caught early. Follow-up at regular intervals with a careful examination by an experienced physician or colon and rectal surgeon is very important to assess the results of treatment and to check for recurrence of anal cancer. Additional studies may also be recommended.