What Is Colorectal Cancer?
Colorectal cancer, one of the most common types of cancer, is the growth of malignant cells in the colon or rectum. Tumors in the colon are slow-growing, but may eventually become large enough to obstruct the digestive tract. The cancer may spread to the liver, lymph nodes, or other parts of the body, and symptoms may not appear until the cancer is quite advanced. However, if the cancer is detected and treated early, the outlook is optimistic.
Who Gets Colorectal Cancer?
Incidence of colorectal cancer is highest in developed countries such as the United States and Japan, and lowest in developing countries in Africa and Asia. According to the American Cancer Society, it is the third most common type of cancer in both men and women in the United States. Incidence is slightly higher in men than women, and is highest in African American men.
The American Cancer Society estimates that about 141,00 cases of colorectal cancer are diagnosed and about 50,000 people die from the disease each year in the United States. The death rate from colon cancer has declined in recent years due to improved screening methods and advances in treatment.
- Often there are no symptoms in early stages.
- Change in bowel habits (constipation, diarrhea, or extremely narrow stools) lasting for more than 10 days.
- Bloody or black, tarry stools.
- Pain or tenderness in the lower abdomen.
- Bloating, cramps, gas pains, and a protracted feeling of fullness.
- Nausea and vomiting
- Loss of appetite and loss of weight.
- Fatigue, paleness (pallor), and heart palpitations due to anemia that often occurs in conjunction with colorectal cancer.
- Inability to pass stools (a sign of intestinal obstruction, an emergency situation).
- The cause of colorectal cancer is unknown.
- The risk of colorectal cancer increases significantly after age 50.
- A personal or family history of colon polyps or ulcerative colitis increases the likelihood of colorectal cancer. A family history of colorectal, breast, or endometrial cancer is also a risk factor.
- A diet high in animal fats (especially from red meat) and low in fiber is associated with a higher incidence of colorectal cancer.
- Obesity, physical inactivity, smoking, and heavy alcohol consumption are also risk factors.
- Ashkenazi Jews have a higher incidence of a specific genetic mutation (called I1307K) that increases the risk for colorectal cancer.
Diagnosis involves screening to detect colorectal cancer in patients without symptoms with no family history of the disease.
Screening is recommended for most average-risk patients beginning at age 50, and for African-American patients beginning at age 45. Screening in other high-risk patients may start early, sometimes as young as ages 10 to 12. Screening includes the following:
- Digital rectal examination (in which the doctor examines the rectum with a gloved finger) and fecal occult blood test (to detect blood in the stool) annually
- Double-contrast barium enema (which creates a sharp image of the colon during x-ray) or “virtual” colonoscopy (a special CAT scan that looks at the colon in a specific way) every 5 years.
- Flexible sigmoidoscopy (used to detect tumors in the lower colon) every 5 years, or
- Total colonoscopy (used to detect tumors throughout the colon) every 10 years.
- A new stool DNA test is available, but the exact interval for how often it must be repeated is unknown.
Diagnosis of colorectal cancer in symptomatic patients and high-risk patients includes laboratory and imaging tests. Biopsy (removal of a tissue sample for examination under a microscope) is necessary to confirm the diagnosis.
Colon cancer should always be suspected (and proper tests conducted) in older men and in post-menopausal women with iron deficiency anemia. In younger men and women with iron deficiency anemia, cancer is less likely but must still be investigated through a doctor’s recommendations.
Surgery is the treatment of choice for colorectal cancer and is necessary to remove the tumor. The type of surgery is determined based on the extent of the disease:
- Radical bowel resection, also called partial colectomy and hemicolectomy, is used to treat 80-90% of colorectal cancer patients. This procedure may be performed through a large incision in the abdomen (called open surgery) or through several small incisions (called laparoscopic surgery).
In this procedure, the tumor is located using a no-touch technique (i.e., the surgeon locates the tumor without manipulating the colon to avoid releasing cancer cells into the bloodstream). The segment of the colon that contains the tumor and the nearby lymph nodes are removed and healthy segments of the colon are reconnected, if possible (called end-to-end anastomosis). Removal of the lymph nodes is called lymphadenectomy.
If the colon cannot be reconnected, a temporary or permanent colostomy, in which an opening (stoma) connects the colon to the surface of the abdomen, is performed allowing waste to pass through into a bag. Approximately 15% of patients require a permanent colostomy.
- Partial hepatectomy (removal of part of the liver) and oophorectomy (removal of the ovaries) are surgical procedures used to treat colorectal cancer that has spread to these organs. Other organs and tissues that may be affected include the stomach, kidneys, small intestine, and abdominal wall.
Chemotherapy and radiation therapy may be used in addition to surgery. Radiation therapy may be used before surgery to reduce the size of the tumor or after surgery to destroy remaining cancer cells; chemotherapy may be used to halt the spread of the cancer.
Immunotherapy, or biological therapy, attempts to stimulate the immune system to fight disease. Some vaccines are being investigated to help the body fight off abnormal cells. More commonly, special man-made antibodies are given to target the abnormal components of the cancer cells and help destroy them.
- Eat a diet low in animal fat and high in fiber.
- A diet high in calcium can help as well.
- Get regular checkups if you have a personal or family history of colon or digestive tract disease.
- Follow your health care provider’s recommendations for colon cancer screening. You should discuss which screening test is best and at what age to start your screening.
When To Call Your Doctor
- Call a doctor if you experience rectal bleeding or if you have changes in your bowel movements that persist for three weeks or more.
- Make an appointment with a doctor if you have a personal or family history of colon disease.
- EMERGENCY Get immediate medical attention if you experience a total inability to pass stools, you have abdominal pain that steadily worsens, or you are passing blood in the stool or vomit.
Reviewed by Jenifer K. Lehrer, M.D., Department of Gastroenterology, Aria-Torresdale Hospital, Aria Health System, Philadelphia, PA. Review provided by VeriMed Healthcare Network.