Risk factors for anal cancer include certain sexually transmitted infections.
Bleeding with bowel movements, pain, and sometimes itching around the anus are typical symptoms.
A manual examination, sigmoidoscopy or colonoscopy, and a biopsy are done to verify the diagnosis.
Treatment may involve either surgery alone or a combination of radiation therapy and chemotherapy or radiation therapy and surgery.
Anal cancer develops in the skin cells of the immediate area around the anus or in the lining of the transitional zone between the anus Rectum and Anus The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus ( see also Overview of the Anus and Rectum). Ordinarily,... read more and the rectum Rectum and Anus The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus ( see also Overview of the Anus and Rectum). Ordinarily,... read more (the anal canal). Unlike in the rectum and the large intestine, in which cancers are almost always adenocarcinomas, cancers of the anus are primarily squamous cell carcinomas.
Anal cancer occurs in about 8,590 people in the United States each year and causes more than 1,350 deaths. Anal cancer is more common among women.
Risk factors for anal cancer include the following:
Receptive anal intercourse
Received radiation therapy on anal skin
Symptoms of Anal Cancer
People with anal cancer often experience bleeding with bowel movements, pain, and sometimes itching around the anus. About 25% of people with anal cancer have no symptoms. In this instance, the cancer is found only during a routine examination.
Diagnosis of Anal Cancer
A doctor's evaluation
Sigmoidoscopy or colonoscopy
To diagnose anal cancer, a doctor first inspects the skin around the anus for any abnormalities. With a gloved hand, the doctor probes the anus and lower rectum, checking for any portions of the lining that feel different from surrounding areas. A flexible sigmoidoscope (a short viewing tube with a camera on the end) is used to evaluate the anus and rectum. An anoscope (a small rigid tube equipped with a light) may be inserted several inches into the anus to assist with examination.
The doctor then removes a sample of tissue from an abnormal area and examines it under a microscope (called a biopsy).
If people have bleeding, doctors may do a colonoscopy to look for a coexisting colon cancer Colorectal Cancer Family history and some dietary factors (low fiber, high fat) increase a person’s risk of colorectal cancer. Typical symptoms include bleeding during a bowel movement, fatigue, and weakness... read more . During a colonoscopy, the entire large intestine is examined. A colonoscopy may be done even in people with who have obvious hemorrhoids Hemorrhoids Hemorrhoids are dilated, twisted blood vessels located in the wall of the lower rectum and anus. The swollen vessels are caused by an increase in pressure. Lumps form inside or outside of the... read more (twisted veins located in the wall of the rectum and anus), which can cause bleeding.
Treatment of Anal Cancer
Combination of radiation with chemotherapy
The treatment and prognosis of anal cancer depends on the extent of the cancer.
Radiation therapy combined with chemotherapy is usually done first.
Surgery is done in people whose cancer does not go away after radiation therapy and chemotherapy or goes away and comes back. With surgery, the doctor must be careful not to interfere with the functioning of the muscular ring that keeps the anus closed (the anal sphincter). The anal sphincter stays closed until the person has a bowel movement. A sphincter that does not function properly could lead to loss of control over bowel movements ( fecal incontinence Fecal Incontinence Fecal incontinence is the loss of control over bowel movements. Fecal incontinence can occur briefly during bouts of diarrhea or when hard stool becomes lodged in the rectum ( fecal impaction)... read more ).
For people whose cancer has not spread, therapy cures many anal cancers, with 70% or more of people surviving longer than 5 years.