Anal Cancer Symptoms

Anal Cancer Symptoms

This article describes common symptoms that may occur from cancer in the anus. There are several different types of anal cancer. Many symptoms that arise from these cancers are similar.

The anal canal is about 4 to 5 cm long. The anus is considered not just the canal but the first inch of skin (anal verge), the muscles around the anus (the anal sphincter complex), and the glands that drain and supply mucus to the anal canal (anal crypt glands). The anal canal undergoes a gradual change from the lining of the colon to cells that are similar to the lining of the skin. During this transition, the nerves that supply the area also change. This is why the muscles near the outside are under voluntary control and sensation is similar to other skin areas compared with the upper part of the anal canal which is less sensitive and not under voluntary control. The drainage of the lymph fluid also changes through this transition zone.

There are many different types of diseases / conditions that might affect the anus including:

  • Cancer
  • Hemorrhoids
  • Infection
  • Fissure
  • Trauma
  • Weakness of muscles
  • Nerve dysfunction
  • Incontinence
  • Venereal (genital) warts caused by HPV (human papilloma virus). Infection with certain strains of HPV increases the risk of cancer

It has been estimated that a large percent of anal cancers are caused by HPV, especially type 16. HPV is a common infection which resolves in most people, but can cause a number of cancers. Sexual abstinence, monogamy, and condom usage can lower the risk of HPV infection and therefore anal cancer.

There is now a vaccine available called Gardasil® that can prevent most cases of HPV that lead to anal cancer. It is FDA approved to prevent anal cancer and recommended for both teenage girls and boys. It is highly recommended that these vaccines be given before teenagers become sexually active.

There are also many different types of cancers that can affect the anus. A partial list of the common anal tumors includes:

  • Bowen’s Disease
  • Paget’s Disease
  • Basal Cell Cancer
  • Anal Margin Cancer
  • Squamous Cell Cancer
  • Verrucous Cancer
  • Melanoma
  • Adenocarcinoma
  • Epidermoid Cancer

There is some overlap of these tumor types because they can occur in different areas of the anus and thus comprise a slightly different disease type.

Pruritus: Symptoms of anal cancers can be quite varied. A common symptom of the anal region is itching (also known as pruritus). Anal pruritus can be caused by a variety of non-cancer causes such as infection, poor hygiene, or hemorrhoids. Anal pruritus tends to be a self-perpetuating cycle because the more the area itches, the skin is abraded by itching causing more discomfort, and so on. It is usually not caused by cancer.

Bleeding: Blood seen in the anal region or with bowel movements is never normal and should never be dismissed as just “hemorrhoids.” The problem arises in determining the source of the blood. The blood might have come from the anal region, a fissure, a colon tumor, or even a bleeding ulcer in the stomach. Proper evaluation of these will often include a physical examination and a colonoscopy. Bleeding that occurs with pain is commonly due to a benign cause called anal fissure. Anal fissure is a very small tear in the outside skin of the anus that can cause severe pain with some bleeding. Anal tumors can also cause pain and bleeding. When an anal tumor causes pain it is usually from invasion of nerves in the pelvis or near the anus and generally signifies an aggressive tumor.

Mass: Many anal tumors will cause a mass that can be felt by the person with the tumor or by an examining physician. Larger anal tumors may be visible as well. The feeling of a mass in the anal area is never normal and should be investigated. A mass in the anal canal may interfere with passage of stool and create constipation. An anal mass might occur either on the skin around the sphincter, on the sphincter itself, or just inside the external sphincter in the anal canal. There are other masses that might occur in this region that are not cancer such as hemorrhoids, viral infectious growths (such as HPV), and infection (e.g. perianal abscess).

Change in bowel habits: At times the only symptom that may occur is change in the frequency of bowel movements or difficulty in moving the bowels. These are also important symptoms that should not be overlooked. While dehydration or lack of fiber in the diet can cause these, they are never normal and should be given proper attention. Tumors of the colon, rectum or anus can cause difficulty with bowel movements.

Weight loss: Most cancers will cause some degree of weight loss as they grow. In a very simplistic explanation, cancers are very active and use a lot of calories to grow. Cancers also release hormones that may cause poor appetite and contribute to weight loss. Unexplained weight loss with a cancer generally means it is advanced in stage (i.e. not confined to the mucosa).

Pain : Pain in the anal area might arise from a variety of reasons such as anal fissure, anal trauma, constipation, infection, and cancer. When pain occurs with a cancer this is generally a bad sign and means the tumor is invading local nerves. Again, pain in the anal region is commonly referred to as “my hemorrhoids acting up.” This is a common misconception as only thrombosed external hemorrhoids will cause pain. The vast majority of hemorrhoids are not painful, just uncomfortable.

Unfortunately, some anal cancers will occur without symptoms until they are quite advanced such as anal melanoma. Many anal cancers are very treatable if detected early. Anal squamous cell carcinoma is often curable without surgery by treatment with a combination of chemotherapy and radiation therapy (a.k.a. nigro protocol therapy). Some anal tumors are treated like a rectal cancer in that they require a combination of surgery and multimodal therapy that usually includes chemotherapy and radiation. Small, confined anal tumors may be treated just with a minor surgery to remove it.


  1. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed. Chapter 51. New York, NY: Saunders.
  5. Cameron JL; Cameron AM. (2010) Cameron: Current Surgical Therapy, 10th ed. Chapter 196. Philadelphia, PA: Elsevier Saunders
  6. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.

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