OakLeaf Medical Network Healthy Viewpoints, Winter 2003
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Thomas Peller, MD

You Can Reduce Your Cancer Risk

By Thomas Peller, MD, Southside Medical Clinic

In 2002, there were approximately 150,000 patients diagnosed with colorectal cancer (CRC) and 56,600 deaths. The lifetime risk of developing CRC in the United States is 6%. The cancer will be fatal in half of all patients diagnosed. Currently, CRC is the third most common cancer diagnosed in the United States and the third most common cause of cancer-related deaths.

The cause of colon cancer is not known, but it is felt that both genetic and environmental factors play a role. Genetic factors include family history, while environmental factors include obesity, smoking and most importantly, diet. High fat and low fiber diets increase the risk of CRC while a low fat and high fiber diet may be protective against CRC. Age also is a risk factor with greater than 90% of patients being diagnosed after the age of 50. Despite known risk factors only 30% of patients diagnosed with colorectal cancer have identified risk factors.

Screening for colorectal cancer has been shown to be very effective in reducing death from colon cancer. This is because:

  • Almost all colorectal cancers arise from premalignant lesions called adenomatous polyps.
  • There is good evidence to show that removal of theses adenomas prevents colorectal cancer.
  • Colon cancer found early has a cure rate greater than 90%, while colon cancer found at an565658 advanced stage has cure rates less than 50%. Unfortunately, almost 60% of all CRC is diagnosed with at least regional advanced disease.

A variety of tests have now been recommended to screen for CRC. Current
recommendations are to begin screening at age 50 unless there is a family history of adenomas or CRC. In patients with a family history, screening begins at age 40, or 10 years younger than the youngest person at the time of their diagnosis.

The most commonly employed tests are:

  • Fecal occult testing done yearly
  • Flexible sigmoidoscopy every five years
  • Fecal occult yearly coupled with sigmoidoscopy every five years
  • Colonoscopy every ten years

Fecal occult testing requires a special diet that is free of red meat. It is usually used in conjunction with flexible sigmoidoscopy. Patients who have a positive test have an increased risk of advanced cancer and should have a full colonoscopy performed.

The sigmoidoscopy is an office-based procedure usually performed every five years. It examines the distal third of the colon. It does require special training. If a polyp or cancer is found, then a full colonoscopy should be performed to rule out other associated lesions in the proximal colon and to remove any polyps found.

The colonoscopy is the most invasive method of screening for CRC, but it also is the most through and is the only method that is able to remove polyps at the time of the procedure. If a screening colonoscopy is normal, then the next exam is usually performed in ten years. This is because indirect evidence suggests that it takes on average, 10 years for a polyp less than 1 cm (roughly 1/3 of an inch) to change from an adenoma to colon cancer. Colonoscopy is the most common method used in patients who have a family history of CRC.

Colonoscopy does require a bowel preparation consisting of a day on a liquid diet and an oral laxative. In the past a gallon of liquid purge was required as the laxative. Now, most patients can get by with 3 ounces of an oral liquid laxative or a series of 20 pills taken over an hour followed by 40 ounces of water. Most patients are sedated for this procedure and will need a driver to take them home after the procedure.

Colonoscopy requires the most extensive training of the methods discussed. The ability to examine the whole colon; completely remove polyps, and have low risk of complications depends upon the training and experience of the endoscopist.

Gastroenterologists are the most highly trained of the specialists performing this type of exam.

Regardless of which type of screening test is employed, it is important that people know that CRC screening can reduce death from colorectal cancer and that the use of any of the screening tests is better than no screening at all.

For more information, call Dr. Peller, Gastroenterologist at Southside Medical Clinic: 715.830.9990 / www.southsidemedicalclinic.com