Rectal Cancer

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is rectal cancer?

Rectal cancer starts in the rectum, the last portion of the colon, or large intestine. The rectum is located in the pelvis, and is where stool is stored until it is emptied through the anus. About 40,000 people are diagnosed with rectal cancer each year in the United States (Source: ACS).

With early diagnosis, which is possible through screening tests, rectal cancer has an excellent prognosis and can be treated with surgery, chemotherapy and radiation. Screening tests to detect rectal cancer include a digital rectal exam, fecal occult blood test to look for microscopic amounts of blood in the stool, and colonoscopy or sigmoidoscopy to look directly at the lining of the rectum and colon. Symptoms of rectal cancer can involve a change in bowel movements, blood in the stool, lower abdominal pain, and weight loss.

While it is not known what causes rectal cancer, it is more common among people who are over 50 and have a family or personal history of colorectal cancer, have polyps or inflammatory conditions of the intestines, have a diet low in fiber and high in fat, or who smoke. Not everyone who has risk factors develops rectal cancer, and sometimes it occurs in people who do not have risk factors. Ten percent of cases occur in people under the age of 50 years.

Rectal cancer is a serious disease. Although it rarely creates conditions that need to be evaluated in an emergency setting, tell your doctor right away if you suspect you may have rectal cancer. Seek prompt medical care if you notice changes in your bowel movements, bloody stool, persistent lower abdominal pain, or unexpected weight loss. Seek immediate medical care (call 911) for significant rectal bleeding.

What are the symptoms of rectal cancer?

Rectal cancer may not have any symptoms initially, but as it continues to grow, the rectum may narrow and changes in bowel movements may occur. If the tumor starts to bleed, blood may be seen in the stool. Pain may develop in the lower abdomen and pelvis and other nonspecific symptoms such as weight loss may occur.

Common symptoms of rectal cancer

Symptoms of rectal cancer include:

  • Abdominal bloating or cramping
  • Bloody stool (the blood may be red, black, or tarry in texture)
  • Constipation
  • Diarrhea
  • Fatigue
  • Lower abdominal or pelvic pain
  • Nausea with or without vomiting
  • Pain or difficulty having a bowel movement, or incomplete emptying of the bowel
  • Sensation of fullness of the bowel
  • Thin stool
  • Unexplained weight loss

Serious symptoms that might indicate a life-threatening condition

Rectal cancer can lead to serious complications, some of which can be life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have significant rectal bleeding. Seek prompt medical care for any of the following symptoms:

  • Bloody stool (the blood may be red, black, or tarry in texture)
  • Pencil-thin stool
  • Persistent changes in bowel movements
  • Persistent full sensation in the bowels
  • Unexplainable fatigue
  • Unexplained weight loss

What causes rectal cancer?

Cancer occurs when abnormal cells reproduce in an uncontrolled fashion. It is not known what causes this to occur, although risk factors have been identified for several cancers including rectal cancer.

What are the risk factors for rectal cancer?

A number of factors increase the risk of developing rectal cancer. Not all people with risk factors will get rectal cancer. Risk factors for rectal cancer include:

  • Age over 50

  • Chronic alcohol use or abuse

  • Familial adenomatous polyposis (FAP) (an inherited condition in which many polyps develop in the colon and the risk of colorectal cancer is increased)

  • Family history of colorectal or breast cancer

  • Hereditary nonpolyposis colorectal cancer (HNPCC) (an inherited condition associated with an increased risk of colorectal and other types of cancer but not with the formation of multiple polyps in the colon)

  • High-fat, low-fiber diet

  • Inflammatory bowel disease (including Crohn’s disease and ulcerative colitis)

  • Personal history of polyps in the colon or of colorectal or other types of cancers

  • Sedentary lifestyle

  • Smoking

Reducing your risk of rectal cancer

You may be able to lower your risk of rectal cancer by:

  • Decreasing alcohol consumption

  • Eating a healthy diet high in fruits and vegetables

  • Quitting smoking

  • Getting regular exercise

How is rectal cancer treated?

Treatment of rectal cancer begins with seeking regular medical care throughout your life. Regular medical care allows a health care professional to provide early screening tests. Regular medical care also provides an opportunity for your health care professional to promptly evaluate symptoms and your risks for developing rectal cancer.

Goal of cancer treatment

The goal of rectal cancer treatment is to permanently cure the cancer or to bring about a complete remission of the disease. Remission means that there is no longer any sign of the disease in the body, although it may recur or relapse later. Early rectal cancers may be treatable with surgery alone. More advanced rectal cancers may warrant additional treatment with radiation therapy and chemotherapy.

Common treatments for rectal cancer

Common treatments for rectal cancer include:

  • Chemotherapy to attack cancer cells

  • Participation in a clinical trial testing promising new treatments for rectal cancer

  • Radiation therapy to attack cancer cells

  • Surgery to remove the cancer

  • Targeted therapy to attack cancer cells

Other treatments for rectal cancer

Other therapies may be added to help with your general state of health and any complications of the cancer or its treatment. Such therapies include:

  • Antinausea medications if nausea occurs

  • Consultation from a wound, ostomy and continence nurse if a portion of the bowel has been removed and an ostomy created to allow stool to be emptied through the abdominal wall

  • Dietary counseling to help maintain strength and nutritional status

  • Pain medications as needed to increase comfort

  • Palliative care to improve the overall quality of life for patients with serious disease and their families

  • Physical therapy to help strengthen the body, increase alertness, reduce fatigue, and improve functional ability during and after cancer treatment

Complementary treatments

Some complementary treatments may help some people to better deal with rectal cancer and its treatments. These treatments, sometimes referred to as alternative therapies, are used in conjunction with traditional medical treatments. Complementary treatments are not meant to substitute for traditional medical care. Be sure to notify your doctor if you are consuming nutritional supplements or homeopathic (nonprescription) remedies as they may interact with the prescribed medical therapy.

Complementary treatments may include:

  • Acupuncture

  • Massage therapy

  • Nutritional dietary supplements, herbal remedies, tea beverages, and similar products

  • Yoga

Hospice care

In cases in which rectal cancer has progressed to an advanced stage and has become unresponsive to treatment, the goal of treatment may shift away from curing the disease and focus on measures to keep a person comfortable and maximize the quality of life. Hospice care involves medically controlling pain and other symptoms while providing psychological and spiritual support as well as services to support the patient’s family.

What are the potential complications of rectal cancer?

Complications of untreated rectal cancer can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of rectal cancer include:

  • Anemia (low red blood cell count)

  • Bowel obstruction

  • Spread of cancer to other parts of the body such as the liver or lungs

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 18
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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