Definition

Rectal cancer is cancer in the rectum, the last part of the large intestine. The rectum allows waste to pass through the anal canal and out of the body.

Causes

Cancer occurs when cells in the body divide without control or order. Eventually, these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths invade nearby tissues and spread to other parts of the body. It is not clear exactly what causes these problems in the cells, but is probably a combination of genetics and the environment.

Risk Factors

Being over 50 years of age increases your chance of rectal cancer. Other factors that may increase your chance of rectal cancer include:

  • Genetics
  • History of colon or rectal cancer, or polyps
  • Family history of colon or rectal cancer, especially a parent, sibling, or child
  • Radiation therapy for prostate cancer
  • Obesity
  • Smoking
  • Diet high in fat and low in fiber
  • Heavy alcohol intake
  • Physical inactivity

Symptoms

In most cases, there are no symptoms with rectal cancer. When symptoms do appear, they may include:

  • A change in bowel habits
  • Blood, either bright red, or black and tarry, in the stool
  • Stools that are narrower than usual
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • General abdominal discomfort, such as frequent gas pains, bloating, fullness, and/or cramps
  • Unexplained weight loss
  • Constant feeling of fatigue or tiredness

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. Your rectum will be checked for lumps or abnormal areas.

Your stool may be tested. This can be done with:

  • Blood tests
  • Fecal occult blood test
  • Biopsy

Your bodily structures may need to be viewed using an instrument. This can be done with:

Images may be taken of your bodily structures. This can be done with:

Treatment

Talk with your doctor about the best treatment plan for you. Treatment may include one or more of the following options:

Surgery

Surgery is the main treatment for rectal cancer. There are several options for surgery depending on the location of the cancer and how much it has spread:

  • Polypectomy and local excision—Early stage removal of the cancer.
  • Local transanal resection—Removal of the cancer with a margin of surrounding healthy tissue.
  • Transanal endoscopic microsurgery (TEM)—Removal of the cancer in the rectal wall with surrounding healthy tissue. The hole in the wall is sewn back together.
  • Low anterior resection—Removal of the cancer, surrounding healthy tissue, and lymph nodes for cancers high in the rectum, closer to the colon.
  • Proctectomy—Removal of the rectum. This surgery also involves attaching the end of the colon to the anal canal in order to preserve bowel function.
  • Abdominoperineal resection—Removal of rectum, anal canal, and surrounding tissue.
  • Pelvic exenteration—Removal of rectum, anal canal, and nearby organs with cancer, such as the prostate, uterus, or bladder.

Some surgeries may require temporary or permanent colostomies. A colostomy is a surgical opening through the wall of the abdomen into the colon. This is used as a path for waste material to leave the body. After a colostomy, you will wear a special bag to collect body waste. If the bladder is removed, you will also need a urostomy. A urostomy is an opening in the abdominal wall that allows for the passage of urine.

Radiation Therapy

Radiation is used to kill cancer cells and shrink tumors. It is directed at the site of the tumor from a source outside the body. This therapy is aimed at the immediate area of the cancer. It is used alone or with chemotherapy.

Chemotherapy

This therapy uses drugs to kill cancer cells. It may be given in many forms, including pill, injection, and via a catheter. Drugs enter the bloodstream and travel through the body killing cancer cells. They can also kill healthy cells. This therapy is systemic, meaning it affects your entire body.

Medications

Targeted Therapy

Targeted therapy uses medications to target and kill cancer cells, while sparing healthy tissue. They are currently used to treat advanced cancers. Targeted therapy is less harmful to healthy tissue, which reduces side effects. It may be used alone or in combination with chemotherapy.

Other Medications

Some medications can be used as part of a treatment plan. Other medications may help to either prevent or reduce side effects of treatments, or to manage certain side effects if they occur. These include:

  • Corticosteroids
  • Blood stem cell support medications
  • Anti-nausea medications
  • Nonsteroidal anti-inflammatory medications such as ibuprofen
  • Opioids

Tell your doctor when you notice a new symptom, and ask if any of these medications are right for you.

Prevention

Screening

The causes of most cancers are not known. However, it is possible to prevent many colon and rectal cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women at average risk should follow one of the following screening options:

  • Colonoscopy every 10 years
  • Flexible sigmoidoscopy every 5 years
  • CT colonography every 5 years
  • Double-contrast barium enema every 5 years
  • Stool DNA test every 3 years
  • Annual fecal occult blood test (FOBT)
  • Annual fecal immunochemical test (FIT)

People with any of the following risk factors should begin colon and rectal cancer screening earlier and/or undergo screening more often:

  • African Americans or Native Americans
  • Strong family history of colon or rectal cancer, or polyps
  • Family history of hereditary colon or rectal cancer syndromes
  • History of colon or rectal cancer, or adenomatous polyps
  • History of chronic inflammatory bowel disease

Be sure to discuss colon cancer screening with your doctor to see how and when you should be screened.

Lifestyle Changes

There are also lifestyle changes that may reduce your risk of rectal cancer. These include:

  • Not smoking
  • Drinking alcohol in moderation—no more than 2 drinks a day if you are a man, and no more than 1 drink a day if you are a woman
  • Eating a healthy diet high in fruits, vegetables, and whole grains, and low in red meat
  • Being physically active by exercising at least 30 minutes a day on most days of the week
  • Maintaining a healthy weight