population-based studies such as the Cancer Prevention Study II Nutrition cohort.158 Fecal DNA for colorectal cancer screening in the elderly A recent study comparing Hemoccult II with abnormal DNA detection in asymptomatic patients, the majority of whom were older than 65 years, suggests statistically significant improvement in the sensitivities for colorectal cancer and adenomas with high-grade dysplasia (51.6% vs 12.9% and 40.8% vs 14.1%; P = .003 and P < .001). This improvement using multitarget analysis of fecal DNA was achieved without sacrificing specificity.159 The use of DNA testing, with its increased sensitivity over Hemoccult II, may replace fecal occult studies but is a screening test used in conjunction with and not in place of colonoscopy. Its role in screening the elderly population may be to allow more precise selection of those needing therapeutic colonoscopy. The prospect of a simple, noninvasive test for cancer detection in the older population would encourage and facilitate screening for one of the most common neoplasms in the elderly. Characteristics of the DNA tests, frequency of testing, acceptability to older patients, and other issues need to be addressed. However, this is an area of investigation that may make colorectal screening easier and more accessible for the elderly and most affected population. Age-Associated Changes in Hepatic and Biliary Function There is no effect of age on conventional liver function tests, such as serum concentrations of aminotransferases, hepatic alkaline phosphatase, and bilirubin. However, dynamic assessments of liver function do show a decrease with aging. In healthy subjects, liver size, blood flow, and perfusion decrease by 30%–40% between the third and 10th decade.160 Aminopyrine demethylation, galactose elimination, and caffeine clearance decrease in parallel with the reduction in liver volume and blood flow. Studies in isolated perfused livers from young adult and senescent rats show age-associated reductions of approximately 50% in bile acid–dependent and independent bile flow, hepatocellular uptake of taurocholate, and rate of bile acid secretion. Tight junction permeability and transcellular transport were modestly decreased in senescent rats.161 However, the senescent liver may be more susceptible to stress insult from diet, alcohol consumption, tobacco use, nutritional status, coexistent diseases, and genetic factors. Liver injury is associated with a regenerative response characterized by increased hepatocyte mitogen-activated protein kinase activity. Aged animals have an age-associated decline in mitogen-activated protein kinase activity and epidermal growth factor–stimulated hepatocytes.162 Specific impairment of intracellular transcription factors that are involved in transduction of growth hormone receptor activation have been reported in senescent mice.163 Interestingly, mitogenic stimulation of these pathways in aged mice results in hepatic regeneration following partial hepatectomy that is equivalent to that seen in younger animals.164 This has potential implications for management of hepatic resection in older patients, such as that used in treatment of solitary hepatoma. Hepatic damage may also be related to accumulation of oxidative metabolites with age, because animal studies indicate that some species have significantly increased hepatic lipid peroxidation by 23 months.165 Recognition and management of liver disease in aged patients There are several key differences