May 18th, 2009
08:39 PM ET

Fast Facts on Cancer

[cnn-photo-caption image=http://i2.cdn.turner.com/cnn/2009/HEALTH/04/09/anal.cancer.fawcett/art.fawcett.gi.jpg caption="Farrah Fawcett, shown here in 2004, learned she had cancer in 2006."]

The Mayo Health Clinic

Anal cancer is an uncommon type of cancer that occurs in the anal canal. The anal canal is a short tube at the end of your rectum through which stool leaves your body.

About 5,000 people in the United States are diagnosed with anal cancer each year, according to the National Cancer Institute. The incidence of anal cancer is increasing, though it isn't clear why.

Most cases of anal cancer are diagnosed at an early stage — when treatment provides the best chance for a cure. Most people with anal cancer are treated with a combination of chemotherapy and radiation.

What is anal cancer?
Normally, cells in the body will grow and divide to replace old or damaged cells in the body. This growth is highly regulated, and once enough cells are produced to replace the old ones, normal cells stop dividing. Tumors occur when there is an error in this regulation and cells continue to grow in an uncontrolled way. Tumors can either be benign or malignant. Although benign tumors may grow in an uncontrolled fashion sometimes, they do not spread beyond the part of the body where they started (metastasize) and do not invade into surrounding tissues. Malignant tumors, however, will grow in such a way that they invade and damage other tissues around them.

They also may spread to other parts of the body, usually through the blood stream or through the lymphatic system where the lymph nodes are located. Over time, the cells within a malignant tumor become more abnormal and appear less like normal cells. This change in the appearance of cancer cells is called the tumor grade, and cancer cells are described as being well-differentiated, moderately-differentiated, poorly-differentiated, or undifferentiated. Well-differentiated cells are quite normal appearing and resemble the normal cells from which they originated. Undifferentiated cells are cells that have become so abnormal that often we cannot tell what types of cells they started from.

Anal cancer is a malignant tumor of either the anal canal or anal verge. In the United States, 80% of anal cancers are squamous cell cancers,, resembling the cells found in the anal canal., This is not true in other parts of the world, however. In Japan, 80% of anal cancers are adenocarcinomas, resembling the glandular cells seen in the rectum. Cancers of the anal verge may be referred to as “perianal skin cancers,” because they usually behave more like skin cancers than like anal cancers. They may respond more poorly to treatment than other forms of anal cancers. Perianal skin cancers represent about 25% of all anal cancers. Occasionally, other types of cancer, such as melanoma, Kaposi’s sarcoma, and lymphoma may develop in the anus. These other types of cancer will be discussed separately, and will not be addressed further in this review.

Anal cancers frequently begin as anal dysplasia. Anal dysplasia is made up of cells of the anus that have abnormal changes, but do not show evidence of invasion into the surrounding tissue. The most severe form of anal dysplasia is called carcinoma in situ. In the case of carcinoma in situ, cells have become cancerous, but have not begun to invade normal tissue yet. Over time, anal dysplasia changes to the point where cells become invasive and gain the ability to metastasize, or break way to other parts of the body. Anal dysplasia is sometimes referred to as anal intraepithelial neoplasia (AIN), or a “pre-cancer”. When anal cancer does spread, it most commonly spreads through direct invasion into the surrounding tissue or through the lymphatic system. Spread of anal cancer through the blood is less common, although it can occur.

What causes anal cancer and am I at risk?
Each year, there are approximately 4,000 cases of anal cancer in the United States. In general, the incidence of anal cancers has been increasing over the past 30-40 years. The vast majority (~85%) of cases are in Caucasians. The incidence of anal cancer increases with age: patients with anal cancer have an average (median) age of 62 years. Cancers of the anal canal are more common in women, while the incidence of cancers of the anal verge is roughly equal in both men and women.


Filed under: 360° Radar • Health Care
soundoff (12 Responses)
  1. Dennis

    As a cancer survivor you have to stay strong, Its tuff, but you have great support with Ryan and the rest of the Nation. I love you, and pray for your recovery.

    May 18, 2009 at 11:32 pm |
  2. stella mosley

    I feel that Farrah has a very wonderful spirit and a very strong will to live. She is an inspiration to those who are facing all types of cancer, may God continue to give her the strength she need at this time to fight this disease.

    May 18, 2009 at 8:53 pm |
  3. Paul G. Pagnini, M.D.


    Thank you so much for having a public discussion about anal cancer. I am a radiation oncologist at The USC/Norris Cancer Hospital and the Los Angeles County/USC Medical Center. I have treated about 50 cases of anal cancer in the past 5 years alone. One of the largest demographics of increasing cases is coming from HPV (Human Papilloma Virus) infected gay males. As Human Immunodeficiency Virus (HIV) becomes a chronic treatable illness these men are living long enough to eventually develop anal squamous cell cancer (much like the risk of cervical cancer with HPV infected females). If caught early and treated properly there is a 60%-90% cure rate with chemotherapy and radiation therapy alone. Unfortunately so many people are embarrassed or ill at ease to bring up early symptoms with their doctor. The only way we can break down the stigma is to have open and public discussions; hopefully someday our society will be at ease enough about this topic to also wear ribbons and go on charitable walks, to help fight this important battle.

    May 18, 2009 at 8:48 pm |
  4. Seacilia Mundy

    I've avoided getting checked and never have been to exam but now I am going to make an appointment. And honestly due to Farrah's Story I will take it seriously. I could not watch the documentary as I've lost both parents to cancer and I want to remember her as friendly, nice and well.

    May 18, 2009 at 8:17 pm |
  5. Annie Kate

    I had not heard of this type of cancer before so appreciate the facts given in your article. I am very sorry that Farrah Fawcett has it; I hope for the best for her.

    May 18, 2009 at 7:59 pm |
  6. Gloria Bullock

    Thank you so much for all this good information on anal cancer. It answered many questions that i had and would never ask. I have one question. Would a colonoscopy discover anal cancer? thank you

    May 18, 2009 at 7:13 pm |
  7. Isabel

    It is very sad to see the disease win.
    It is very sad to know that we will lose someone so special

    May 18, 2009 at 6:59 pm |
  8. Megan Dresslar - Shoreline, WA

    I have tumor benign inside, I went to doctor and she felt my stomach and went to ultrasound if there have a tumor. Doctor found my tumor benign inside uterus, I like to know people who have cancer and wear pink ribbon, I have lot of issue, when I learned that she send e-mail to me , Just found bit small tumor benign, I will have to talk other doctor what he have decide best for me, maybe surgery or laser.... I like to say thank you for your message to support to beat cancer...... hope you have take call doctor and appointment. Take care women!!! Thanks for sharing me this message.

    May 18, 2009 at 6:59 pm |
  9. marcia bunn


    May 18, 2009 at 6:32 pm |
  10. Evelyn

    I grew up looking up to Farrah in the 70's and 80's. Because of her, I am still a Charlie's Angels' freak. She is beautiful and gracious. May the Lord protect her through this valley of difficulty, and may she be showered with love and tender loving care.

    May 18, 2009 at 6:31 pm |
  11. Patricia bricker

    can anal cancer be diagnosed by colonoscopy?
    Is rectal exam done by gyn specialist /pap exam able to find problem?/

    May 18, 2009 at 5:40 pm |
  12. Louis Burgdorf

    Why is no one asking the “man of peace” Cat Stevens about his condemnation of Salomon Rushdie and his call for the death of that man?

    May 18, 2009 at 5:24 pm |