Overview
Colorectal cancer includes cancer of the colon and rectum, the two organs that make up the large intestine. Colon cancer and rectal cancer are often grouped together because they have many characteristics in common.
Colorectal cancer is the fourth most common cancer in men and women. More than 97,000 colon cancer cases and about 43,000 rectal cancer cases are diagnosed each year in the U.S.
The good news is that the death rate from colorectal cancer has been declining over the last several decades. Several factors are contributing to this decrease: a rise in the number of screening colonoscopies has led to the removal of many colorectal polyps before they can develop into cancer; the disease is being detected early when it is easier to treat; and treatment for advanced disease has become more effective.
Symptoms
Colorectal cancer doesn't typically cause symptoms in the early stages of the disease. When some of the symptoms listed below do appear, they may vary, depending on the size and location of the tumor.
- Change in bowel habits, including diarrhea or constipation, or change in consistency or color of stool that lasts longer than four weeks
- Rectal bleeding or blood in the stool
- Persistent abdominal discomfort, including gas, cramps and pain
- Feeling as if the bowel doesn't empty completely
- Weakness or fatigue
- Unexplained weight loss
- Abdominal fullness even after not eating for a while
- Unexplained iron deficiency (anemia) in men or in postmenopausal women
Causes
The cause of colorectal cancer is not clear. Some inherited gene mutations may increase the risk for the disease but only a small percentage of people with the disease have these genetic mutations.
Risk Factors
Some of the behaviors, characteristics and family history that may increase the risk of developing colorectal cancer include:
- Older age - the majority of people with colon cancer are over 50
- African-American race - people of African-American descent have a higher risk
- Inflammatory intestinal conditions - ulcerative colitis, Crohn's disease and irritable bowel disease
- Presence of premalignant polyps in the colon and rectum
- Inherited syndromes - familial adenomatous polyposis and Lynch syndrome
- Family history of colorectal cancer
- Diet high in calories, animal proteins and saturated fats
- Diet low in fiber
- High alcohol consumption
- Lack of physical activity
- Obesity
- Smoking
- Radiation therapy to the abdomen for previous cancers
Prevention
People with an average risk for colorectal cancer should start screening at age 50. Those with a higher risk of developing the disease should start sooner. Colonoscopies are considered the best type of diagnostic tool for colorectal cancer, but there are other options. Talk with a physician to learn about less invasive screenings.
Polyps are growths that develop in the colon. At times, they can develop into malignant tumors. Polyps can be removed during colonoscopies, helping to prevent colorectal cancer.
Regular, moderate exercise has been shown to decrease a person's risk of developing colon cancer.
A diet rich in fiber, fruit and vegetables and complex carbohydrates with a minimum of red and processed meat lowers the risk for colon cancer. Eating less saturated fats while consuming more good quality fats, olive oil, fish oil and avocado also help decrease the risk.
Tests and Diagnoses
A colonoscopy is the best way to help prevent colorectal cancer, and an extremely effective method in finding the disease at an early stage. A long, slender flexible tube with a video camera is used to view the entire colon and rectum. If suspicious areas are found, the physician can pass surgical tools through the tube to take tissue samples and remove polyps.
Stages of Colorectal Cancer
Stage 0 - Called carcinoma in situ; abnormal cells are in the innermost tissue of the small intestine called the mucosa.
Stage 1 - The cancer has spread beyond the lining of the colon or rectum but hasn't spread beyond the colon wall or rectum.
Stage 2 - The cancer has spread to or through the colon wall or rectum but hasn't spread to lymph nodes.
Stage 3 - The cancer has spread to the lymph nodes but not to other organs.
Stage 4 - The cancer has invaded other organs.
Treatment
Treatment depends on the size, location and stage of the disease. Surgery is typically done when colon cancer is in the early stage. Chemotherapy, radiation, targeted drug therapy, immunotherapy, ablation or a combination of approaches is used for the more advanced stages. New advances have led to prolonged life and better quality of life for those with the disease.
