Prevention and early detection of colorectal cancer--new horizons

Colorectal cancer is potentially one of the most preventable malignancies. Nutritional awareness (low fat, low red meat, high fruits and vegetables) and regular physical activity have major potential for primary prevention of this malignancy, while early detection technologies have the potential of both influencing mortality from colorectal cancer as well as enhancing primary prevention through detection and removal of lesions that could potentially develop into cancer. While the potential for prevention is large, its materialization is far from being optimal. The large-scale lifestyle changes in the population necessary to reduce colorectal cancer rates are hard to achieve, and most of the early detection technologies are either invasive or otherwise nonappealing to the population. Thus, without abandoning the proven prevention methods, new avenues need to be investigated to deal with this malignancy, which carries both high morbidity and high mortality. Such new avenues can now be followed, both in prevention and detection. Chemoprevention, or the use of medications to prevent disease, has now been extensively explored in colorectal cancer. Some of these interventions, such as supplemental fibers, have failed to demonstrate the anticipated effect, while others such as calcium supplementation have been shown to reduce formation of premalignant lesions, polyps, or adenomas. Data accumulating in recent years have suggested that aspirin, nonsteroidal anti-inflammatory drugs, and selective COX-II inhibitors all have a potential to reduce both colorectal cancer and colorectal adenomas. Issues of safety and therapeutic indexes have recently come up as barriers to the use of COX-II inhibitors, and have again drawn attention to aspirin as a potential drug of choice. Association studies have also shown a major potential role for statins in colorectal cancer prevention. New methodologies in cancer detection involve the introduction of colonography or virtual colonoscopy, and the development of methods of detection of genetic somatic mutations in feces or peripheral blood. While radiological techniques currently avoid the need for premedication and are less invasive, they currently still require similar gut cleansing to colonoscopy, can also lead to perforation, are costly, and carry a non-negligible exposure to radiation. Genetic analysis of the stool for mutations in tumor cells is evolving as a promising technique, struggling to achieve both high sensitivity and high specificity with the right combination of mutations sought. With all of these developments taking place, the near future will undoubtedly bring about the expected reduction in colorectal cancer mortality.