Colorectal cancer is the second leading cause of cancer death in the US. According to the American Cancer Society (ACS), approximately 105,500 new cases of colon cancer and 42,000 new cases of rectal cancer will be diagnosed in 2003 in the United States. Combined, they will cause about 57,100 deaths.

The American Cancer Society (ACS) and many other organizations have long recommended screening colonoscopies in patients over the age of 50, as a means of reducing the mortality rate of colorectal cancer by identifying and removing cancerous or suspicious polyps at an early stage.

However, little research has been done regarding the risk factors for advanced colorectal cancer. Recently, a group of researchers decided to try and identify these risks factors in order to help physicians develop strategies for reducing the risk of advanced colorectal cancer in their patients.

The results of their study, published in the December 10, 2003 issue of the Journal of the American Medical Association, found that there were several important risk factors for advanced colorectal cancer that could be modified to help patients reduce their risk.

About the study

The researchers enrolled 3121 asymptomatic participants between the ages of 50 and 75 years of age who had no lower gastrointestinal (GI) tract symptoms. All the participants also underwent a complete colonoscopy to determine whether or not they had advanced colon cancer.

The researchers also collected information regarding family history, prior cholecystectomy (gallbladder removal), use of nonsteroidal or antiinflammatory drugs (NSAIDs), body mass index, level of physical activity, smoking, alcohol use, cholesterol levels, and dietary factors (fat intake level and type, dietary fiber intake, and vitamin intake).

The findings

Of the 3121 study participants:

  • 1441 (46.2%) had no colon polyps
  • 118 (3.8%) had noncancerous polyps
  • 391 (12.5%) had hyperplastic (precancerous) polyps
  • 842 (27.0%) had small cancerous tumors (> 1 millimeter (mm) in diameter)
  • 329 (10.5%) had advanced colon cancer (at least one cancerous tumor < 10 mm in diameter)

The researchers then compared the 1441 participants who had no polyps with the 1680 who had polyps or cancer. They found that the risk factors most commonly associated with advanced colon cancer were those who had a family history of colon cancer, those who smoked, and those who drank moderately to heavily. They also found that those who ate diets high in cereal fiber (> 4.2 grams (g) per day), diets rich in vitamin D (> 645 international units (IU) per day), or used nonsteroidal antiinflammatory drugs on a daily basis (NSAIDS) appeared to have the lowest risk for colon cancer.

Risk factors that moderately reduced the participants’ risk of colon cancer included higher levels of physical activity, daily multivitamin use, higher levels of calcium intake, and lower consumption of red meat.

Factors that had no affect on the participants’ risk of colorectal cancer were body mass index (BMI), prior cholecystectomy, or cholesterol level.

How does this affect you?

The researchers identified a number of risk factors for advanced colorectal cancer in asymptomatic individuals. These risk factors include:

  • Family history of colon cancer
  • Smoking
  • Moderate to heave alcohol use
  • Low fiber diets
  • Diets lacking in vitamin D or calcium

While we can’t do anything about our parents, we can do something about of these other risk factors. While this kind of study has a number of limitations, it is certainly reasonable for physicians to use this list as basis for advising their patients, particular those with a family history of colorectal cancer.

The study also points out the high prevalence of polyps and colorectal cancer in asymptomatic people. You can still get cancer even if you have none of these risk factors. While knowing your risk is helpful, modifying your risk is no substitution for regular colorectal screening. If you’re over fifty or have a family history of colorectal cancer or polyps, see your doctor about being screened.

If you have a history of colorectal cancer (personal of familial) and you have one or more of these risk factors, speak with your physician to see if he or she may be able to recommend ways you can reduce your risk of disease.