What Is Anal Cancer?

Medically Reviewed by Jennifer Robinson, MD on March 24, 2024
3 min read

Anal cancer is an uncommon malignancy that starts in the anus -- the opening at the end of the rectum.

The American Cancer Society estimated that 10,540 cases of anal cancer will be diagnosed in 2024 and about 2,190 deaths may occur that year from anal cancer.

By contrast, some 106,5900 people are predicted to be diagnosed with colorectal cancer in the U.S. in 2024, and about 46,220 people are predicted to die of the disease the same year.

Approximately half of all anal cancers are diagnosed before the malignancy has spread beyond the primary site, whereas 13% to 25% are diagnosed after the cancer has spread to the lymph nodes, and 10% are diagnosed after the cancer has spread to distant organs, or has metastasized.

When it is found early, anal cancer is highly treatable.

The overall five-year survival rate following diagnosis of anal cancer is 64%.

Most anal cancers (80%) are diagnosed in people who are over age 60. Prior to age 35, anal cancer is more common in men. However, after age 50, anal cancer is slightly more common in women.

The incidence rate of anal cancer is six times higher in single men as compared to married men.

Receptive anal intercourse is strongly related to the development of anal cancer.

Anal infection with human papillomavirus (HPV) resulting in genital warts is a major risk factor for the cancer.

Immunocompromised patients, such as those with HIV disease, are prone to get anal cancer. In this subgroup, the prognosis is worse than for non-immunocompromised patients.

Gardasil, one of the HPV vaccines originally approved for the prevention of cervical cancer, is also approved for the prevention of anal cancer in men and women.

The most common symptom associated with anal cancer is bleeding.

Because anal itching can also be a symptom of the cancer, many people initially attribute their bleeding and itching to hemorrhoids. This can delay the diagnosis of anal cancer.

Other signs and symptoms of anal cancer may include:

  • Pain or pressure in the anal area
  • Unusual discharges from the anus
  • Lump near the anus
  • Change in bowel habits

Anal cancer may be detected during a routine digital rectal exam or during a minor procedure, such as removal of what is believed to be a hemorrhoid.

The cancer may also be detected with more invasive procedures such as an anoscopy, proctoscopy, or endorectal ultrasound.

If cancer is suspected, a biopsy should be done and the specimen examined by a pathologist.

Staging workup may include an abdominal and pelvic CT scan, a pelvic MRI scan to assess the pelvic lymph nodes, a chest x-ray, and liver function studies. PET scans are sometimes performed.

Anal cancer is primarily treated with a combination of chemotherapy and radiation. Surgery is typically reserved for patients failing the above therapy.