Anal Cancer

Benign (non-cancerous) growths, pre-cancerous polyps and cancers can develop in the anus, the tube-like canal that connects the rectum to the outside of the body. Anal cancer is a malignant tumor of either the anal canal or anal verge, a transitional zone between the skin of the anal canal and the perianal skin. Infection with the human papillomavirus (HPV) can affect the risk of anal cancer. Possible symptoms include bleeding from the anus or rectum or a lump near the anus. While the prognosis depends upon the size of the tumor and whether it has spread to lymph nodes, treatment for anal cancer is often very effective.

Anal cancer is fairly rare. The American Cancer Society estimates that fewer than 5,000 individuals annually will be diagnosed with anal cancer. The vast majority of new cases are in Caucasians, with women affected more than men. 

Our patients with anal cancer are treated at the Moores Gastrointestinal Cancer Unit. See the Gastrointestinal Cancer Unit for more information.

You can also review the tabs at top of this page for information on anal cancer symptoms, risks, and treatment.

Symptoms

Symptoms may include:

• Bleeding from the anus or rectum
• Pain or pressure
• Itching or discharge
• A lump near the anus
• A change in bowel habits

Risks

Among the risk factors associated with anal cancer are:

• Individuals age 50+
• Having multiple sexual partners
• Anal intercourse
• Infection with the human Papilloma virus (HPV)
• Infection with the human immunodeficiency virus (HIV)
• Smoking
• Individuals diagnosed with benign conditions such as anal fistulae (abnormal openings), anal fissures, perianal abscesses or hemorrhoids

Radiotherapy

There are various types of radiation, or radiotherapy, used by radiation oncologists, depending upon the circumstances, according to Catheryn Yashar, M.D., a radiation oncologist with expertise in gastrointestinal cancers. Electrons may be used, if possible, to spare underlying tissue because they don’t penetrate deeply. Two types of photon therapy sometimes used for anal cancer are Intensity Modulated Radiation Therapy (IMRT) and Image-Guided Radiation Therapy (IGRT).

IMRT is a sophisticated treatment that conforms the radiation dose and the radiation intensity, thereby minimizing dosage to surrounding normal tissue and reducing the risk of acute and chronic side effects.

IGRT is a major change in the practice of radiation oncology. Before IGRT, patients were usually imaged (internal pictures taken) at the beginning of treatment and only periodically during treatment. Now, patients can be imaged every day, immediately prior to each treatment, to ensure that therapy is accurately delivered. In coming years, these images will potentially be used to adapt treatment to changes in the tumor and patient.

Chemotherapy

Several chemotherapeutic agents exist to treat anal cancer. The most commonly used drug is 5-flourouracil (5-FU) with either mitomycin C or cisplatin. Because patients respond differently to medications, we’ll carefully monitor your chemotherapy and make adjustments as needed. An experimental treatment available in UCSD clinical trials is the use of antibodies to recognize proteins that are preferentially expressed on the surface of tumor cells.

UCSD often uses chemotherapy in conjunction with radiotherapy to treat gastrointestinal tumors such as anal cancer.

Surgery

While surgery was the primary treatment for anal cancer many years ago, it is less frequently used today. When surgery is required, the tumor will be cut from the anus, with the sphincter muscles left intact whenever possible. In advanced cancer cases, a surgeon may sometimes need to remove the anus, rectum and part of the colon through an incision made in the abdomen.