(Colon Cancer; Cancer of the Colon and Rectum)
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 tissues and can spread to other parts of the body. A benign tumor does not invade or spread.
The cause of colorectal cancer is unknown. However, research shows that certain risk factors are associated with the disease.
A risk factor is something that increases your chance of getting a disease or condition.
- 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
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.
The doctor will ask about your symptoms and medical history, and perform a physical exam.
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 rectum and 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
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.
Surgery (the main treatment for colorectal cancer) –Colectomy, or surgical removal of the cancerous tumor and nearby colon or rectum tissues, 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) – the use of radiation to kill cancer cells and shrink tumors. Radiation is directed at the colon from a source outside the body.
Chemotherapy – 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 – the use of medications or substances made by the body to increase or restore the body's natural defenses against cancer. Also called biological response modifier (BRM) therapy.
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 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 years
- Colonoscopy every 10 years
People with any of the following risk factors should begin colorectal cancer screening earlier 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