(Colon Cancer, Cancer of the Colon and Rectum)
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 regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. 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
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 fat and 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 Crohn’s disease
• Other risk factors include: obesity, physical inactivity, diabetes, smoking, alcohol intake, nightshift work, and 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 completely, lasting for more than a few days in people over age 50
• Blood (either bright red or very dark) in the stool
• Stools that are narrower than usual
• Abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
• Unexplained weight loss
• Constant fatigue
Note: These symptoms may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor.
Diagnosis
The doctor will ask about your symptoms and medical history and perform a physical exam.
Tests include:
Digital Rectal Exam—use of a physician's gloved finger to examine the rectum for lumps or growths
Fecal Occult Blood Test—a test to check for hidden blood in the stool
X-rays (Using Barium, Called a Barium Enema )—pictures of the large intestine that show polyps or other changes
Sigmoidoscopy—an examination of the lower colon using a lighted tube called a sigmoidoscope
Colonoscopy—examination of the rectum and entire colon using a lighted tube called a colonoscope
Polypectomy—the removal of a polyp during a sigmoidoscopy or colonoscopy
Biopsy—the removal of colon or rectal tissue to be tested for cancer cells
CT (Computerized Tomography) or Magnetic Resonance Imaging (MRI) and More Recently Positron Emission Tomography (PET)—to identify the spread of the tumor ouside the colon
Treatment
Once 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 (Colectomy)
Surgery is the main treatement for colorectal cancer. It requires surgical removal of the cancerous tumor and nearby colon or rectum tissue, and possibly nearby lymph nodes. In 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 that is worn on the outside of the body.
Radiation Therapy (Radiotherapy)
Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. Radiation is directed at the colon from a source outside the body.
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.
Biological Therapy (Biological Response Modifier Therapy)
Biological therapy is the use of medications or substances made by the body to increase or restore the body's natural defenses against cancer.
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 test
• Flexible sigmoidoscopy every 3-5 years
• Yearly fecal occult blood test or fecal immunochemical test plus flexible sigmoidoscopy every 5 years
o 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 years
• Colonoscopy 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:
• A strong family history of colorectal cancer or polyps
• A known family history of hereditary colorectal cancer syndromes
• A personal history of colorectal cancer or adenomatous polyps
• A personal history of chronic inflammatory bowel disease
