Well, you might ask, what is an anesthesiologist/intensivist doing reviewing two studies and an editorial on colonoscopic screening for colorectal cancer? Probably just showing my age, but this is an important topic for all of us aging types, even those of us who yearn to remain eternally young.

Colorectal cancer is the second most common cause of death from cancer in North America, surpassed only by lung cancer. Interestingly, unlike other carcinomas, it occurs in higher socioeconomic groups. The bad news is that there has been no change in the incidence or mortality from colorectal cancer in the past fifty years.

Most colon cancers develop over a number of years from adenomatous polyps (as opposed to juvenile or hyperplastic polyps, which are not pre-malignant). The good news is that adenomatous polyps are readily amendable to removal by colonoscopic polypectomy. Therefore, the U.S. Preventive Services Task Force, the American Cancer Society, and various multidisciplinary expert panels all recommend screening for colorectal cancer. There is extensive data that early screening of asymptomatic, average risk patients starting at age 50 can reduce mortality from colon cancer. Current recommendations advocate screening with occult blood analysis (stool guaiac testing annually) or flexible sigmoidoscopy (flex sig) every several years. Barium enema evaluation is obtained on occasion as an alternative to flex sig and colonoscopy. Although colonoscopy is generally performed only in symptomatic patients, higher risk patients (see table), or those with positive screening tests, some experts suggest consideration of routine colonoscopy for all patients age 50 or older.

Slightly less than half (46%) had totally normal exams while 54% had one or more lesions. Of these, about a third (1171/3196 patients) had one or more adenomas or cancers. Ten percent had advanced lesions and 1% had invasive cancer. As expected, the incidence of advanced neoplasia increased with age and family history. Less than 1% of patients (0.3%) had serious complications. Roughly 1 in 30 to 40 patients (2.7 – 3.7%) had normal distal exams (area seen on routine flex sig either to the sigmoid colon or splenic flexure), but still had an advanced lesion in the proximal or right side of the colon. Therefore, the majority of patients with a normal flex sig and advanced proximal disease would have been missed on routine screening with flex sig.

Limitations of this study include the male predominance of patients and its short-term nature. The authors were unable to determine if full colonic screening lowered the mortality rate for colon cancer compared to other screening techniques.

The second study by Imperiale and colleagues was performed in 50-year-olds or older who were members of the health plan of Eli Lilly, the Indiana-based, pharmaceutical company. The goals of the study were to determine the relative risk of advanced proximal neoplasia in patients with distal polyps as compared to patients with no distal polyps and, secondly, to identify the risk of large proximal lesions according to findings in the distal colon. The patients in this study were slightly younger than the VAH study (mean age 59.8 vs. 62. 9) and there was a much larger percentage of woman (41.1 % vs. 3%). Patients had a similar success rate of completed colonoscopies to the cecum. Cancer and premalignant lesions were identified more frequently in older men than in women. Advanced neoplastic lesions were found in 1/40 asymptomatic patients in the proximal colon in the presence of normal right colon anatomy. These lesions would have been missed by routine flex sig.

Dr. Daniel Podolsky, Division Chief of Gastroenterology at Massachusetts General Hospital and Mallinkrodt Professor of Medicine at Harvard School of Medicine, reminds us in his accompanying editorial that despite widespread advocacy for screening for colon ca, less than 30% of persons for whom it is recommended actually are screened. This lack of success appears to be multifactorial; aversion to the nature and location of the problem and current screening techniques as well as failure of physicians to implement screening

Dr. Podolsky goes on to emphasize that these two studies show that flex sig frequently fails to detect important colorectal neoplasms and that colonic neoplasms are far more uniformly distributed than previously thought. Although the high success rate from these two studies may not be achieved in real world practice, colonoscopy is a relatively safe procedure with a < 0.2% major complication rate (bleeding, perforation, or complications from excessive sedation). He takes a strong stance and recommends that governmental agencies and insurance carriers support comprehensive colonscopic evaluation of all patients 50 years of age and older. If normal, this exam should be repeated every 5 – 10 years. In his opinion, to continue the use of flex sig as a screening tool would be analogous to performing routine mammography only on one breast.

So although these two large studies are the first of their kind, stop and think about the implications for yourself and loved ones. As an American health care professional, you are in a higher socioeconomic group, you may be in a higher risk group, and like me, you may have family members, friends or colleagues who unfortunately had delayed identification of later stage colorectal ca. They then may have undergone aggressive, but all too frequently unsuccessful therapies for advanced lesions such as radiation, chemotherapy, or cryosurgery. As Ben Franklin so wisely opined two hundred plus years ago, "an ounce of prevention is worth a pound of cure."

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