Colorectal Cancer: Screening and Surveillance Recommendations

Being overweight or obese is also associated with a higher risk of CRC, with stronger associations more consistently observed in men than in women. Obesity increases the risk of CRC independent of physical activity. Abdominal obesity (measured by waist circumference) may be a more important risk factor for colon cancer than overall obesity in both men and women [23–25]. Diet and lifestyle strongly influence CRC risk; however, research on the role of specific dietary elements on CRC risk is still accumulating. Several studies, including one by the American Cancer Society, have found that high consumption of red and/or processed meat increases the risk of both colon and rectal cancer [23,26,27]. Further analyses indicate that the association between CRC and red meat may be related to the cooking process, because a higher risk of CRC is observed particularly among those individuals who consume meat that has been cooked at a high temperature for a long period of time [28]. In contrast to findings from earlier research, more recent large, prospective studies do not indicate a major relationship between CRC and vegetable, fruit, or fiber consumption [28,29]. However, some studies suggest that people with very low fruit and vegetable intake are at above-average risk for CRC [30,31]. Consumption of milk and calcium may decrease the risk of developing CRC [28,29,32].

In November 2009, the International Agency for Research on Cancer reported that there is now sufficient evidence to conclude that tobacco smoking causes CRC [33]. Colorectal cancer has been linked to even moderate alcohol use. Individuals who have a lifetime average of 2 to 4 alcoholic drinks per day have a 23% higher risk of CRC than those who consume less than 1 drink per day [34].

Protective Factors

One of the most consistently reported relationships between colon cancer risk and behavior is the protective effect of physical activity [35]. Based on these findings, as well as the numerous other health benefits of regular physical activity, the American Cancer Society recommends engaging in at least moderate activity for 30 minutes or more on 5 or more days per week.

Accumulating research suggests that aspirin-like drugs, postmenopausal hormones, and calcium supplements may help prevent CRC. Extensive evidence suggests that long-term, regular use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) is asso-ciated with lower risk of CRC. The American Cancer Society does not currently recommend use of these drugs as chemoprevention because of the potential side effects of gastrointestinal bleeding from aspirin and other traditional NSAIDs and heart attacks from selective cyclooxygenase-2 (COX-2) inhibitors. However, people who are already taking NSAIDs for chronic arthritis or aspirin for heart disease prevention may have a lower risk of CRC as a positive side effect [36,37].

There is substantial evidence that women who use postmenopausal hormones have lower rates of CRC than those who do not. A decreased risk of CRC is especially evident in women who use hormones long-term, although the risk returns to that of nonusers within 3 years of cessation. Despite its positive effect on CRC risk, the use of postmenopausal hormones increases the risk of breast and other cancers as well as cardiovascular disease, and therefore it is not recommended for the prevention of CRC. At present, the American Cancer Society does not recommend any medications or supplements to prevent CRC because of uncertainties about their effectiveness, appropriate dosing, and potential toxicity [38–40].