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Colon Cancer

What is colon cancer?

Cancer is a disease where the cell growth of the tumor is uncontrollable and can result in death if not halted by surgery, immunomodulation, radiation or chemotherapy. At its most basic, cancer is the abnormal growth of cells in the body resulting in a tumor or neoplasm. Neoplasms can be benign, usually slower growing, and not likely to spread elsewhere with abnormal growth. Malignant neoplasms are usually faster growing, more likely to spread to other parts of the body and potentially life threatening.

Researchers have known for many years that DNA plays a critical role in turning on and off cell growth. Build up of abnormalities in the DNA with age or environmental factor can activate certain specific “oncogenes” which promote uninhibited cell division, i.e., cancer. Some individuals have mutations which turn on these oncogenes early in life, like with Familial Adenomatous Polyposis, putting them at risk for colon cancer much earlier than average. Most individuals develop these changes over a lifetime of exposure to cigarette smoke, high fat diet, radiation, and environmental chemicals.

Every cancer is individual and these may grow quickly with high rates of cells “breaking off” or metastasizing to other organs causing disability and death or the cancer may be more stable or “indolent”. Research on the causes and treatment of cancer are ongoing, but as yet there are multiple treatments available, but no magic bullet to reverse the process.

Colorectal cancer (CRC) is a type of cancer that specifically starts in the colon or the rectum. About 149,500 new cases are diagnosed yearly in the United States, with about 30% occurring in the rectum and 70% higher in the large bowel/colon. About 52,980 people are expected to die of their colon cancer yearly.

Rates of colorectal cancer mortality/death have been declining since 1990, yet CRC remains the third leading cause of cancer death in women and the second leading cause of cancer in men. Because of a 30% increase in the number of colon cancers diagnosed in patients who are 40 years old, the American Cancer Society and the United States Preventative Services Task Force have changed their recommendation to start screening for this disease now at age 45 in all individuals. 86% of those newly diagnosed below age 50 are symptomatic and this is associated with more advanced disease and worse outcomes. This is definitely a disease you want to catch early for a better chance of treatment and cure!

What factors can put me at higher risk for colon cancer?
  • A history of Inflammatory Bowel Disease such as Crohn’s or Ulcerative Colitis
  • Exposure to abnormal radiation
  • A family history of colon cancer
    • Note that only 20% of colon cancers are associated with a positive relative with the disease.
    • 80% are considered “sporadic” or occurring without genetic predisposition.
  • Inherited syndromes can predispose you to colon cancer
    • Familial Adenomotous Polyposis is a syndrome involving the development of a “carpet” of polyps usually starting after puberty which arises from mutations in the genetic code and result in cancer in nearly 100% of individuals by their late 40’s. It can be associated with multiple cancers in other sites such as liver, thyroid, pancreas and brain. Make sure your gastroenterologist is informed of all relatives with colon cancer, especially if these occur in individuals in their 40’s or younger.
    • MUTYH, Crail’s syndrome, Peutz-Jeghers syndrome, Cowden’s syndrome, Gorlin syndrome, and Cronkhite-Canada syndrome are all genetic associated diseases with increased polyps and cancer predisposition.
  • High fat diet with excessive processed/red meat and a low fiber diet
  • Cigarette/smokeless tobacco and possible alcohol consumption to a lesser degree may be associated
  • Prior cholecystectomy is associated perhaps due to alteration in bile salt composition
What are the symptoms of colorectal cancer?

The highest correlation seems to be for rectal bleeding and weight loss. Symptoms also include:

  • Change in bowel habits (more diarrhea or constipation)
  • Rectal bleeding
  • Abdominal/rectal mass
  • Weight loss
  • Iron deficiency anemia/occult (hidden) anemia
  • Abdominal pain is one of the least common presenting symptoms unless obstruction is present

If the disease is advanced at the time of discovery, invasion into other structures can cause air in the urine stream, bone pain, confusion (with brain metastasis) and a host of other complications. It is best to stay on top of routine screenings to catch the disease before these complications manifest.

How can I screen for colorectal cancer?

If you have symptoms or a positive stool for blood you will need a colonoscopy to define the source of the abnormality and your risk going forward. Fecal immunochemical tests (FIT) for occult blood in the stool or stool guaiac testing can be done annually and are cheap and easy to perform. They identify patients that then require colonoscopy. The dietary restrictions prior to obtaining, the required collection of three for an adequate sample, and physically obtaining and returning specimens to the lab may be drawbacks for some patients.

Flexible Sigmoidoscopy is a shorter, less invasive test which screens the last 1/3 of the colon and can find the majority of colon cancers. It does not require sedation but needs to be combined with a barium enema to evaluate the entire colon, usually once every 5 years.

Cologard or Stool DNA testing uses genetic abnormalities to screen for colon cancer prior to referral to colonoscopy for confirmation/removal of polyps. While the test is quite accurate for the discovery of colon cancer, it has less efficacy in identifying advanced polyps. It has to be repeated once every 3 years.

CT colonography or Virtual Colonoscopy is only available in a limited number of centers throughout the country. It requires a bowel prep with contrast and air filled colon to produce a virtual “flythrough” view of the colon for the operator to identify polyps for removal. Bowel prep has to be thorough as small polyps can be mimicked by adherent stool. It is also repeated once every 5 years.

Colonoscopy is considered the “gold standard” of diagnostic tests and can be therapeutic allowing for removal of polyps at the time of discovery, See the Anderson website for full details concerning this test. With a good prep and no polyps discovered average risk colonoscopy only needs to be repeated once every 10 years. The test does require a bowel prep and sedation to tolerate the insertion of the colonoscope, so it may not be appropriate for all patients.

What can I do to protect myself from colorectal cancer?
  • Eat a high fiber diet— increasing whole grain fiber by 10 grams/day can decrease risk by 10%, Not all studies support this intervention
  • Vitamin supplementation with Folic acid, B6/pyridoxine, Vitamin D, and magnesium have been noted as possibly helpful
  • Increased fish and garlic consumption are beneficial in some studies
  • Increased coffee intake
  • Daily regular aspirin and other non-steroidal agents can reduce the risk of colon adenomas by 20-40% in some studies
  • Increased physical activity has been shown to be helpful
  • Other medications that show promise in decreasing risk of colon cancer include: hormone therapy in women, statin (used for cholesterol lowering), antioxidant vitamins and angiotensin II inhibitors (typically used for blood pressure).

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