Colorectal cancer is the second most deadly cancer in the United States, killing more than 55,000 Americans in 2005. By the time symptoms of colorectal cancer emerge, the cancer is often past the point where it can be cured. As a result, screening for colorectal cancer (through either colonoscopy or a combination of fecal occult blood testing plus flexible sigmoidoscopy ) is an important way to reduce colorectal cancer deaths. Most organizations recommend that individuals can safely delay screening until age 50, unless there is a strong family history of colon colorectal cancer.

In an article published in the March 27, 2006 Archives of Internal Medicine , researchers report that men and women who drink and smoke develop colorectal cancer almost eight years earlier than those who do not drink or smoke. The findings raise the possibility that these higher-risk individuals might benefit from beginning screening at an earlier age.

About the Study

The researchers analyzed the medical records of 166,172 men and women who died of colorectal cancer between 1993 and 2003. The records contained the patient’s age at diagnosis as well as the patient’s sex and alcohol and tobacco use. The researchers defined current smokers and drinkers as those who had smoked or drank alcohol in the year prior to their cancer diagnosis.

Current smokers and drinkers developed colorectal cancer significantly earlier (an average of 7.8 years) than men and women who had never smoked or drank alcohol. Current drinkers were diagnosed 5.2 years younger than never drinkers, and current smokers were diagnosed 5.2 years earlier than never smokers. In addition, current smokers and drinkers were significantly more likely to have distal colorectal cancers (cancers of the lower left part of the colon and the rectum) and all men were significantly more likely to have distal cancers than women.

This study was limited because it did not take family history into account. It also did not consider socioeconomic status and education level, which are known to affect preventive health behaviors such as participation in screening.

How Does This Affect You?

This study found that sex and alcohol and cigarette use affects the age of diagnosis with colorectal cancer, as well as the likelihood of the cancer being located distally versus proximally (in the right side of the colon). Few things in life are truly “one size fits all,” and this study suggests that risk factors other than family history should be used to determine when screening should begin for colorectal cancer.

Physicians should also consider a patient’s risk for distal versus proximal colorectal cancer when advising their patients whether to opt for a flexible sigmoidoscopy or a full colonoscopy. A sigmoidoscopy is less expensive and can be done in a doctor’s office, but it misses proximal tumors. A colonoscopy is more expensive and requires a visit to the hospital, but it can detect tumors throughout the colon, distal and proximal.