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Definition
Colorectal cancer is a disease in which cancer cells grow in the colon and/or rectum. The colon and the rectum are parts of the large intestine, which is part of the digestive system.
Cancer occurs when cells in the body (in this case colon or rectum cells) divide without control or order. Normally, cells divide in a controlled manner. If cells keep dividing uncontrollably, a mass of tissue, called a growth or tumor, forms. The term cancer refers to malignant tumors, which can invade nearby tissue and spread to other parts of the body. A benign tumor does not invade or spread.
Colon Cancer
2008 Nucleus Medical Art, Inc.
Causes
The cause of colorectal cancer is unknown. However, research shows that certain risk factors are associated with the disease.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. Risk factors include:
- Age: 50 or older
- Diets high in beef and fat, low in fiber
- Polyps (benign growths) in the colon and rectum (especially due to familial polyposis, an inherited condition)
- Personal history of colorectal cancer
- Family history of colorectal cancer, especially a parent, sibling, or child
- Ulcerative colitis (inflammation of the lining of the colon) or Crohns disease
- Long-term insulin use in people with type 2 diabetes (associated with an increased risk)
- Other risk factors include:
- Obesity
- High body mass index (BMI)
- Physical inactivity
- Diabetes
- Smoking
- Alcohol intake
- Nightshift work
- Ethnic background
Symptoms
Colorectal cancer often does not have any symptoms, but some symptoms associated with colorectal cancer include:
A change in bowel habits such as diarrhea, constipation, or feeling that the bowel does not empty completelylasting for more than a few days in people aged 50 and older Blood (either bright red or very dark) in the stoolStools that are narrower than usualAbdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)Unexplained weight lossConstant fatigueThese symptoms may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor. DiagnosisThe doctor will ask about your symptoms and medical history and perform a physical exam. Tests include: Digital rectal examuse of a physician's gloved finger to examine the rectum for lumps or growthsFecal occult blood testa test to check for hidden blood in the stool X-rays (using a barium enema) pictures of the large intestine that show polyps or other changes Sigmoidoscopyan examination of the lower colon using a lighted tube called a sigmoidoscope Colonoscopyexamination of the rectum and entire colon using a lighted tube .called a colonoscope Polypectomythe removal of a polyp during a sigmoidoscopy or colonoscopy Biopsythe removal of colon or rectal tissue to be tested for cancer cells Computerized tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET)to identify the spread of the tumor outside the colon TreatmentOnce colon cancer is found, staging tests are performed to find out if the cancer has spread and, if so, to what extent. Treatment depends on the stage of the cancer.
Treatments include: Surgery Surgery is the main treatment for colorectal cancer. It requires surgical removal of the cancerous tumor and nearby colon or rectum tissue, and possibly nearby lymph nodes. ColectomyIn most cases, the doctor reconnects the healthy portions of the colon or rectum. If they cannot be reconnected, a temporary or permanent colostomy is necessary. Colostomy is a surgical opening through the abdomen into the colon through which body waste is collected in a special bag. This bag is worn on the outside of the body. Radiation Therapy Radiation Therapy is the use of radiation to kill cancer cells and shrink tumors. Radiation is directed at the site of the tumor from a source outside the body. It is used alone or in combination with chemotherapy in rectal cancer. Chemotherapy Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy may be given in many forms, including pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells. Prevention The cause of most colorectal cancer is not known. However, it is possible to prevent many colon cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women at average risk for the development of colorectal cancer should follow one of the five screening options listed below:
Yearly fecal occult blood test or fecal immunochemical testFlexible sigmoidoscopy every 3-5 years Yearly fecal occult blood test or fecal immunochemical test plus flexible sigmoidoscopy every 5 years Of the above options, the American Cancer Society prefers the third one.Double contrast barium enema (x-rays of the colon and rectum) every 5 yearsColonoscopy every 10 years People with any of the following risk factors should begin colorectal cancer screening earlier at age 40 and/or undergo screening more often: Strong family history of colorectal cancer or polypsKnown family history of hereditary colorectal cancer syndromesPersonal history of colorectal cancer or adenomatous polypsPersonal history of chronic inflammatory bowel disease RESOURCES: American Cancer Societyhttp://www.cancer.org CancerCarehttp://www.cancercare.org CANADIAN RESOURCES: Public Health Agency of Canadahttp://www.phac-aspc.gc.ca/new_e.html Radiology for Patientshttp://www.radiologyinfo.ca References: American Cancer Society website. Available at: http://www.cancer.org/docroot/home/index.asp . Casciato DA. Manual of Clinical Oncology . 5th. ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004.
Colon carcinoma. EBSCO Dynamed website. Available at: http://www.ebscohost.com/dynamed/what.php . Accessed March 18, 2008. National Cancer Institute website. Available at: http://www.cancer.gov/ . Last reviewed May 2008 by Mohei Abouzied, MDPlease be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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