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21 August 2012 Annals of Internal Medicine Tip Sheet

Annals of Internal Medicine is published by the American College of Physicians on the first and third Tuesday of every month. These highlights are not intended to substitute for articles as sources of information. For a copy of an article, call 215-351-2653 or e-mail Angela Collom at acollom@acponline.org

1. Colonoscopy-related Factors More Important Than Polyp Characteristics for Predicting Colorectal Cancer Risk

Published research suggests that colonoscopy saves lives through detection and removal of adenomas, or benign tumors. Patients who have adenomas removed during colonoscopy are at higher risk for recurring adenomas and colorectal cancer than those who have had a negative colonoscopy. Studies to determine patient risk factors for recurring adenomas and colorectal cancer have focused on characteristics of the adenoma, but characteristics of the colonoscopy had not been considered. Researchers used data from a previously published population-based screening study of 3,148 patients with colorectal cancer and 3,274 control participants to determine the role of both colonoscopy and polyp characteristics in the risk for colorectal cancer. The authors identified 155 case participants and 260 control participants who had a physician-validated colonoscopy with detection of polyps within the past 10 years. The researchers found that colonoscopy-related factors, such as lack of complete removal of all polyps and lack of surveillance colonoscopy within five years, was a more important indicator of future colorectal cancer than polyp characteristics. Overall, two in five cancer cases could be attributed to the presence of one or more of the colonoscopy-related factors, whereas one in five cancer cases were attributable to the presence of one or more high-risk polyps. The researchers conclude that these findings emphasize the importance of optimizing procedural aspects of colonoscopy.

2. Data Suggest No ‘Safe’ Level of Lead Exposure

At high levels of exposure, lead is known to have many negative effects on the human body. Blood lead levels of less than 1.21 µmol/L are considered acceptable, but recent research indicates that even at those levels patients may be at increased risk for chronic kidney disease progression and cardiovascular mortality. Researchers studied survey results for 6,153 patients aged 40 and older with no known kidney disease to determine whether blood lead levels within the range currently considered acceptable are associated with gout. The researchers found that blood lead levels as low as approximately 0.06 µmol/L are associated with increased prevalence of gout, independent of other major risk factors. The researchers suggest further refinement in national goals for prevention, detection, and removal of lead from the environment.

3. Liverpool Lung Project Proves Accurate at Identifying Patients Who Will Benefit from Lung Cancer Screening

Lung cancer is often diagnosed at an advanced stage, when treatment options are less effective. Therefore, survival rates are poor. The National Lung Screening Trial, or NLST, showed a 20 percent decrease in lung cancer deaths and a 6 percent decrease in all-cause mortality when smokers were screened annually for three years with low-dose spiral computed tomography (CT) compared with standard chest radiography. The challenge to clinical practice is to find an accurate risk model for predicting which patients would benefit most from screening. The Liverpool Lung Project (LLP) is a risk model developed to identify smokers’ and nonsmokers’ absolute five-year risk for lung cancer. Researchers evaluated the accuracy of the LLP against the European Early Lung Cancer (EUELC) model and Harvard case-control studies. The researchers found that the LLP risk model was simple and discriminating. It had good ability to distinguish persons who will or will not develop lung cancer, and it performed better than smoking duration or family history as a tool for deciding which persons to screen.