Rectal Cancer

General Information | Treatment Options | Screening
Prevention | Additional Resources

General Information
  • About
  • Risk Factors
  • Signs & Symptoms
  • Detection
  • Stages

Rectal cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum.

The rectum is part of the body's digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Age and family history can affect the risk of developing rectal cancer.

The following are possible risk factors for rectal cancer:

  • Age 50 or older.

  • A family history of cancer of the colon or rectum.

  • A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.

  • A personal history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn disease.

  • Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer (HNPCC; Lynch syndrome).

Possible signs of rectal cancer include a change in bowel habits or blood in the stool.

These and other symptoms may be caused by rectal cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

  • A change in bowel habits.

  • Blood (either bright red or very dark) in the stool.

  • Diarrhea, constipation, or feeling that the bowel does not empty completely.

  • Stools that are narrower than usual.

  • General abdominal discomfort (frequent gas pains, bloating, fullness, or cramps).

  • Weight loss for no known reason.

  • Feeling very tired.

  • Vomiting.

Tests that examine the rectum and colon are used to detect (find) and diagnose rectal cancer.

Tests used in diagnosing rectal cancer include the following:

  • Fecal occult blood test: A test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.
    Fecal Occult Blood Test (FOBT) kit to check for blood in stool.

  • Digital rectal exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.

  • Barium enema: A series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. This procedure is also called a lower GI series.

  • Sigmoidoscopy: A procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope (a thin, lighted tube) is inserted through the rectum into the sigmoid colon. Polyps or tissue samples may be taken for biopsy.

  • Colonoscopy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope (a thin, lighted tube) is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy.

  • Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

  • The stage of the cancer (whether it affects the inner lining of the rectum only, involves the whole rectum, or has spread to other places in the body).

  • The patient's general health.

  • Whether the cancer has just been diagnosed or has recurred (come back).

After rectal cancer has been diagnosed, tests are done to find out if cancer cells have spread within the rectum or to other parts of the body.

The process used to find out whether cancer has spread within the rectum or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

  • Digital rectal exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.

  • CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.

  • MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).

  • Sigmoidoscopy or colonoscopy and biopsy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A sigmoidoscope or colonoscope is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy.

  • Endoscopic ultrasound (EUS): A procedure in which an endoscope (a thin, lighted tube) is inserted into the body. The endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

  • Through tissue. Cancer invades the surrounding normal tissue.

  • Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.

  • Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for rectal cancer:

Stage 0 (Carcinoma in Situ)

In stage 0, abnormal cells are found in the innermost lining of the rectum. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I

In stage I, cancer has formed and spread beyond the innermost lining of the rectum to the second and third layers and involves the inside wall of the rectum, but it has not spread to the outer wall of the rectum or outside the rectum. Stage I rectal cancer is sometimes called Dukes A rectal cancer.

Stage II

In stage II, cancer has spread outside the rectum to nearby tissue, but it has not gone into the lymph nodes (small, bean-shaped structures found throughout the body that filter substances in a fluid called lymph and help fight infection and disease). Stage II rectal cancer is sometimes called Dukes B rectal cancer.

Stage III

In stage III, cancer has spread to nearby lymph nodes, but it has not spread to other parts of the body. Stage III rectal cancer is sometimes called Dukes C rectal cancer.

Stage IV

In stage IV, cancer has spread to other parts of the body, such as the liver, lungs, or ovaries. Stage IV rectal cancer is sometimes called Dukes D rectal cancer.

Recurrent Rectal Cancer

Recurrent rectal cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the rectum or in other parts of the body, such as the colon, pelvis, liver, or lungs.

Cancer information from the NCI PDQ service