Quick summary

Colorectal cancer is one of the most common cancers in older adults, and knowing someone's risk is important because early detection is crucial to successful treatment. Age is the biggest risk factor for colorectal cancer; more than 90 percent of people diagnosed with it are over the age of 50. Make a list of the risks that apply to you or the person in your care, then use it to discuss colorectal cancer screening with the doctor.

Tobacco and personal history as colorectal cancer risks

1. Smoking or chewing tobacco

If a person smoked during his younger years, even if he quit at some point, he's more likely to get a host of cancers, including colorectal cancer -- not just lung cancer, as many people assume. In fact, research in the last few years has established a strong connection between smoking and colorectal cancer. A study published in Gastroenterology in February 2008 revealed that smoking doubles the risk of developing colorectal polyps, which experts have long suspected are the underlying cause of most colorectal cancers. The researchers came to the surprising conclusion that 20 to 25 percent of colorectal polyps may be attributed to smoking, and that the risk was significantly greater for high-risk polyps, suggesting that smoking may play an important role in causing polyps to develop into cancer.

2. History of digestive disorders

Polyps -- benign wartlike growths -- in the colon are the red flag doctors look for when screening for colorectal cancer, but other digestive conditions are risk factors as well. If somone has suffered from ulcerative colitis, irritable bowel syndrome, or Crohn's disease, he's at increased risk of developing colorectal cancer due to chronic inflammation of the colon.

3. Family history of colon cancer

If any of a person's immediate family members (parents, siblings, or children) had colorectal cancer, he's somewhat more likely to develop this disease himself. The likelihood goes up if more than one family member had colorectal cancer or if any of his relatives developed the cancer before the age of 50.

4. Previous history of colorectal cancer

If someone has already had colon cancer removed or treated, he's at increased risk for getting new tumors in other areas of the colon or rectum. This is particularly likely if his previous colon cancer diagnosis and treatment occurred prior to the age of 60. In addition, women who've had ovarian or endometrial cancer and men who've had testicular cancer are at higher risk for colon cancer. Men who've had radiation therapy for prostate cancer have an increased risk of rectal cancer.