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Out of all cases of colorectal cancer, some 70% of malignancies occur in the colon (the large intestine) and 30% appear in the rectum. Anal cancer is uncommon, accounting for only 4% of all cancers affecting the digestive tract. It is an often-curable cancer that produces slow-growing tumors and lesions in the anus and nearby anal anatomy.
Anal cancers are skin cancers. The majority of anal cancers are squamous cell carcinomas (in situ or epidermoid), which originate in the first layer of anal tissue and may spread to deeper layers. This type is associated with HPV. About 15% of anal cancers originate in the glands near the anus; this is called adenocarcinoma, or Paget's disease. The remaining anal cancers are basal cell carcinoma and malignant melanoma. Melanoma in the anus is difficult to see and is often discovered at a late stage, after the cancer has spread through layers of tissue.
Incidence; Risk Factors
The American Cancer Society estimated in 2001 that there would be 3500 new cases of anal cancer among men and women, and 500 deaths resulting from it. Cancer of the perianal skin around the anus is more common in men, while tumors of the anal canal more often affect women.
The exact cause of anal cancer is unknown. Aside from general cancer risk factors such as smoking and alcohol consumption, certain risk factors increase a person's risk for developing anal cancer. HPV and anogenital warts are a significant risk factor - both past and current infections. Some strains of HPV that cause larger warts are not associated with cancer.
Other contributory risk factors include:- A family history of colorectal cancer, polyps or inflammatory bowel disease. Approximately 5% of cancers of the colon occur in families with a predisposition to the disease.
- Age. It usually occurs in people over 50.
- Women are at a slightly higher risk than are men.
- Those in industrialised parts of the world are more susceptible.
- It is thought that a high-meat, high-fat, low-fibre diet encourages the production of carcinogens (cancer-causing substances).
Anal cancer affects men and women, but it is the only cancer with a greater prevalence among men who have sex with men (MSM) than in the general population. About 35 in every 100,000 MSM develop anal cancer, compared to less than one in every 100,000 heterosexual men. The risk for anal cancer in HIV-positive men is twice as high as that for HIV-negative MSM.
Signs & Symptoms
Although most lesions are benign, any visible anal sore or bump should be examined. They may be a sign that others have developed in the anal canal. Other signs include the following:- Abnormal discharge from the anus
- Bleeding from the rectum/anus
- Itching of the anus
- Pain or pressure around the anus
- Sore(s) around the anus that do not heal.
Diagnosis & Tests
Anal cancer is diagnosed by means of an anal Pap smear, in which a cotton swab is inserted past the anus and swirled to capture a tissue sample. The tissue cells are examined under a microscope for signs of dysplasia. An abnormal Pap smear shows signs of excessive cell growth and is followed by a colposcopy - the internal examination of specific lesions or areas of cell growth for biopsy. Acetic acid (vinegar) is introduced into the anal canal to prepare the cells before an anoscope (a plastic tube), is inserted. A colposcope is then inserted through the anoscope to visualize the cells in the anus with magnification. The procedure is painless.
During a biopsy, a biopsy forceps is inserted in the suspect tissue to obtain a sample for close examination. Lesions and tumors found during a colposcopy are typically biopsied.
Anal cancer may be discovered during a routine digital rectal exam (DRE), in which a medical professional inserts a gloved finger past the anus to feel for abnormalities.
Staging is the evaluation of the size and location of a tumor to determine a prognosis and appropriate treatment. Initially, abnormal tissue growth is classified as high- or low-grade squamous interepithelial neoplasia (LSIN or HSIN; high- or low-grade abnormal cell growth), or as cancer. This is determined by the biopsy performed during colposcopy.
If cancer is detected, its stages are described in the following way:- Stage 0 Cancer is found only in top layer of anal tissue (squamous cell carcinomas).
- Stage I Cancer has metastasized (spread) beyond first layer of tissue but is smaller than 2cm.
- Stage II Cancer is larger than 2cm but confined to tissue.
- Stage III A Cancer has metastasized to nearby organs (bladder, reproductive) or lymph nodes.
- Stage III B Cancer has metastasized to organs and lymph nodes in the abdomen, groin, or rectum.
- Stage IV Cancer has metastasized to distant organs.
Treatment & Prevention
Treatment depends on the type of tumor and its stage of development. There are three types of conventional treatment:- Surgical resection; may be done with laser surgery (usually Stages 0 - II)
- Radiation (usually Stage II and higher)
- Chemotherapy (usually Stage II and higher.)
Surgery
A local surgical resection (removal) of the tumor and a small amount of surrounding tissue may suffice in cases of Stage 0 cancer, where the cancer has not metastasized and does not affect the sphincters. In later stages, where cancer has spread, a surgeon may perform an abdominoperineal resection to remove affected tissue, lymph nodes, or sections of or organs in the abdomen. This procedure requires a colostomy, wherein the anus is removed and waste is diverted from the colon through a surgically created opening, through the abdominal wall, and to an external bag for disposal. Abdominoperineal resection is used less frequently because radiation and chemotherapy are effective and do not require a colostomy.
Resection can cause anal stenosis (narrowing) of the anal canal and anus due to scar tissue. Surgery is sometimes required to widen the anus and restore proper function.
Radiation
Radiation, the shrinkage of cancerous tumors with energy waves (e.g., X-rays), is performed with external radiation or internal radioactive implants (radioisotopes). Internal radiation using implants (brachytherapy) involves placing plastic-covered radioactive seeds (pellets) inside the anus, near the cancerous tissue, to shrink tissue. The seeds stay in for the appropriate length of time, perhaps permanently, and require fewer trips to the physician's office. Radiation may be combined with chemotherapy. Radiation causes side-effects including loss of control of the sphincter muscle (incontinence), temporary browning of the skin, and fatigue.
Chemotherapy
Chemotherapy involves drug treatment to kill cancer cells. Drugs used to treat anal cancer include 5-fluorouracil (5-FU), mitomycin, and cisplatin, which are administered orally or intravenously. Chemotherapy is a systemic treatment; the drugs enter and travel throughout the body to kill cancer cells wherever they are. All of these drugs (antineoplastic agents) inhibit the normal production and use of deoxyribonucleic acid (DNA), which is needed for cell growth and division. Arrested cell growth results in tumor shrinkage.
Chemotherapy drugs cause acute side-effects, including nausea, fatigue, vomiting, fever, diarrhea, and sensitivity to sunlight. Certain drugs are associated with specific side effects. 5-fluorouracil may cause low white blood cell count, ulcers, and visual problems. Mitomycin is associated with bone marrow, kidney, mucous membrane, and pulmonary toxicity, as well as kidney failure. Cisplatin may cause hearing problems, serious disorientation, and anaphylactic (allergic shock) reactions, including respiratory distress and swelling.
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Signs, symptoms & indicators of Rectal Cancer:
Risk factors for Rectal Cancer: | | | | | Sexually-Transmitted Diseases |  HPV (Human Papilloma Virus) | Most anal cancers are associated with human papillomavirus (HPV), which causes warts on the anus and genitals, similar to cervical and other cancers of the reproductive system. |
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Supplements and Medications |
Counter-indicators:
 Selenium supplementation |
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Rectal Cancer suggests the following may be present:
Recommendations and treatments for Rectal Cancer:
Preventive measures against Rectal Cancer: | | | | | Diet |  High/Increased Fiber Diet| | The Canadian Cancer Society recommends a higher fiber and lower fat diet to help lower the risk of cancer, especially colon and rectal cancers. |
 Increased Fish Consumption| | Study subjects who ate two or more servings of fish weekly had a much lower risk for esophageal, stomach, colon, rectum, and pancreatic cancers than those who avoided fish. In fact, the rates of these types of cancer were 30-50% lower among fish eaters. High fish consumption was also associated with lower risks for cancers of the larynx (30% lower risk), endometrial cancer (20% lower risk), and ovarian cancer (30% lower risk). |
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KEY | | Strong or generally accepted link | | | Weakly counter-indicative |  | | Strongly counter-indicative | | | Likely to help | | | Highly recommended |
GLOSSARY
Abdomen (Abdominal)
That part of the body between the chest and the hips that contains the stomach, intestines, liver, bladder, pancreas and other organs.
Anaphylactic
Intense allergic reaction to a foreign substance.
Benign
Literally: innocent; not malignant. Often used to refer to cells that are not cancerous; they tend to grow slowly and don't spread (metastasize) like cancer tumors do.
Biopsy
Removal of a sample of tissue from a living being for diagnosis. A pathologist later uses a microscope to look for certain features, such as cancer cells, in the sample. A fine-needle aspiration biopsy involves inserting a thin needle to remove a small amount of tissue, sometimes using CT or ultrasound to guide the needle. A core biopsy involves obtaining a sample of tissue with a thick needle or by inserting a thin, lighted tube (laparoscope) into a small incision in the abdomen. Another biopsy method is to remove tissue during an operation.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Centimeter (Centimeters, cm)
A metric unit of length equaling one hundredth of a meter, or ten millimeters. There are 2.54 millimeters in one inch.
Chemotherapy
A treatment of disease by any chemicals. Used most often to refer to the chemical treatments used to combat cancer cells. Chemotherapy is usually given in cycles: a treatment period followed by a recovery period, then another treatment period, and so on. Most anticancer drugs are given by injection into a blood vessel (IV); some are given by mouth. Chemotherapy is a systemic therapy, meaning that the drugs enter the bloodstream and travel throughout the body. Usually, a patient has chemotherapy as an outpatient (at the hospital, at the doctor's office, or at home). However, depending on which drugs are given and the patient's general health, a short hospital stay may be needed.
Colon (Colonic)
The part of the large intestine that extends to the rectum. The colon takes the contents of the small intestine, moving them to the rectum by contracting.
Colorectal Cancer
A cancerous tumor of the large intestine. It is marked by dark, sticky stools containing blood and a change in bowel habits.
Diarrhea
Excessive discharge of contents of bowel.
Discharge (Discharges)
A secretion, of pus for example, from a wound or bodily orifice.
Dysplasia
Abnormal development of tissue.
Esophagus (Esophageal)
Commonly called the "food pipe", it is a narrow muscular tube, about nine and a half inches long, that begins below the tongue and ends at the stomach. It consists of an outer layer of fibrous tissue, a middle layer containing smoother muscle, and an inner membrane, which contains numerous tiny glands. It has muscular sphincters at both its upper and lower ends. The upper sphincter relaxes to allow passage of swallowed food that is then propelled down the esophagus into the stomach by the wave-like peristaltic contractions of the esophageal muscles. There is no protective mucosal layer, so problems can arise when digestive acids reflux into the esophagus from the stomach.
Gland (Glands)
The glandular system is one of the most important and complicated systems of the body. Gland tissue can be either an organ or general tissue that secretes chemicals and there are two types of gland: exocrine and endocrine. Those glands which secrete chemicals through tubules or ducts are called exocrine and include sweat, tear and salivary glands. Ductless glands - part of the endocrine system - secrete special chemicals (hormones) directly into the blood.
Incontinence (Incontinent)
The inability to retain urine in the bladder for a reasonable length of time. It is can be caused by urethral irritation, loss of tone to the basement muscle of the bladder (the trigone), scarification or growths on the urethral lining, nerve damage, or emotional stress.
Intravenous Infusion (IV)
A small needle placed in the vein to assist in fluid replacement or the giving of medication.
Lesion (Lesions)
Any damage to tissue structure or function; an abnormal change in body tissue caused by disease or injury. A scar is a lesion, as is cancer, a stomach ulcer or a pimple.
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Lymph Nodes (Axillary Nodes, Inguinal Nodes, Lymph Gland, Lymph Glands, Lymph Node, Lymphatic)
Small, bean-shaped nodes at various points throughout the body that function to filter the lymph fluid and attempt to destroy the microorganisms and abnormal cells which collect there. The most common locations are the neck (both sides and front), armpit (axillary) and groin (inguinal), but also under the jaw and behind the ears. Swollen or painful lymph nodes generally result from localized or systemic infection, abscess formation, or malignancy. Other causes of enlarged lymph nodes are extremely rare. Physical examination for lymph nodes includes pressing on them to check for size, texture, warmth, tenderness and mobility. Most lymph nodes can not be felt until they become swollen, and then will only be tender when pressed or massaged. A lymph node that is painful even without touching indicates greater swelling. Lymph nodes can usually be distinguished from other growths because they generally feel small, smooth, round or oval-shaped and somewhat mobile when attempts are made to push them sideways. Because less fat covers the lymph nodes in children, they are easier to feel, even when they are not busy filtering germs or making antibodies. Childrens' nodes enlarge faster, get bigger in response to an infection and stay swollen longer than an adult's. Also known (incorrectly) as lymph glands.
Malignant (Cancerous)
Dangerous. Mainly used to describe a cancerous growth -- when used this way, it means the growth is cancerous and predisposed to spreading.
Melanoma
A life-threatening type of skin cancer that occurs in the cells (melanocytes) that produce melanin, the pigment found in skin, hair, and the iris of the eyes.
Metastasize (Metastases, Metastasized, Metastasizes, Metastasizing, Metastatic)
Usually in reference to cancer: to spread, especially destructively.
Nausea
Symptoms resulting from an inclination to vomit.
Neoplasia
The presence of abnormal cells forming a growth or tumor, unable to perform their normal functions, and replacing healthy cells.
Pancreas (Pancreatic)
Opposite the liver and behind the stomach, the pancreas has two main functions - to manufacture various enzymes for digestion, and to release hormones to help control the body's use of carbohydrates. It releases insulin to help each cell absorb glucose to burn as energy. In this way, insulin controls the amount of sugar (glucose) in the blood. Proper pancreatic function is very important: too much, too little, or no insulin production can be life-threatening. Some of the chemicals released by the pancreas are not hormones, but stimulate other glands to make hormones. Once again, balance is necessary. Nutritional requirements for the pancreas are many. Research indicates that chromium vitamins C, E, B-complex, calcium, magnesium and potassium are especially important.
Prognosis
A prediction (estimate) of the future course and outcome of a disease and an indication of the likelihood of recovery from that disease.
Scar Tissue
Fibrous tissue replacing normal tissues destroyed by injury or disease.
Staging
Although grading and the identification of cancer cell types help determine a patient's prognosis, most doctors believe that the cancer's stage is a better indicator of a patient's survivability. The grade of a cancer cell is an assessment of its appearance compared to that of a normal, healthy cell. Grading is done on a scale (such as 1 to 4) with grade 1 cells differing little from normal cells, typically spreading slowly, and having a good prognosis for treatment. The highest grade cells look extremely different and indicate an aggressive cancer with poor prognosis. Staging allows a physician to gauge the size and location of tumors by using information gathered from imaging studies such as CT scans and MRIs, and from pathology tests and physical examinations. Staging factors that influence a patient's prognosis are:- Spread to tissues surrounding the kidney
- Spread to contiguous organs
- Spread to nearby lymph nodes
- Distant metastasis.
Ulcer (Ulceration, Ulcers)
Lesion on the skin or mucous membrane.
Uterus (Uterine)
The part of the female reproductive system specialized to allow the implantation, growth and nourishment of a fetus during pregnancy.
White Blood Cell (WBC, White Blood Cells)
A blood cell that does not contain hemoglobin: a blood corpuscle responsible for maintaining the body's immune surveillance system against invasion by foreign substances such as viruses or bacteria. White cells become specifically programmed against foreign invaders and work to inactivate and rid the body of a foreign substance. White blood cells are composed primarily of neutrophils, monocytes and lymphocytes. Lymphocytes are either T-cells or B-cells. T-cells (CD3 cells) are divided into T-helper (CD4 cells) and T-suppressor/cytotoxic (CD8 cells) cells.
X-rays (X-ray)
High-energy radiation used to take pictures of areas inside the body.
Last updated: Jun 28, 2008
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