Dennis J. Ahnen

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BACKGROUND AND METHODS The role of colonoscopy in screening for colorectal cancer is uncertain. At 13 Veterans Affairs Medical Centers, we performed colonoscopy to determine the prevalence and location of advanced colonic neoplasms and the risk of advanced proximal neoplasia in asymptomatic patients (age range, 50 to 75 years) with or without distal(More)
Serrated lesions of the colorectum are the precursors of perhaps one-third of colorectal cancers (CRCs). Cancers arising in serrated lesions are usually in the proximal colon, and account for a disproportionate fraction of cancer identified after colonoscopy. We sought to provide guidance for the clinical management of serrated colorectal lesions based on(More)
BACKGROUND Laboratory and epidemiologic data suggest that aspirin has an antineoplastic effect in the large bowel. METHODS We performed a randomized, double-blind trial of aspirin as a chemopreventive agent against colorectal adenomas. We randomly assigned 1121 patients with a recent history of histologically documented adenomas to receive placebo (372(More)
CONTEXT Severe gastroesophageal reflux disease (GERD) is a lifelong problem that can be complicated by peptic esophageal stricture and adenocarcinoma of the esophagus. OBJECTIVE To determine the long-term outcome of medical and surgical therapies for GERD. DESIGN AND SETTING Follow-up study conducted from October 1997 through October 1999 of a(More)
BACKGROUND & AIMS Limited data exist regarding the actual risk of developing advanced adenomas and cancer after polypectomy or the factors that determine risk. METHODS We pooled individual data from 8 prospective studies comprising 9167 men and women aged 22 to 80 with previously resected colorectal adenomas to quantify their risk of developing subsequent(More)
CONTEXT Laboratory and epidemiological data suggest that folic acid may have an antineoplastic effect in the large intestine. OBJECTIVE To assess the safety and efficacy of folic acid supplementation for preventing colorectal adenomas. DESIGN, SETTING, AND PARTICIPANTS A double-blind, placebo-controlled, 2-factor, phase 3, randomized clinical trial(More)
CONTEXT Lynch syndrome is the most common form of hereditary colorectal cancer (CRC) and is caused by germline mutations in DNA mismatch repair (MMR) genes. Identification of gene carriers currently relies on germline analysis in patients with MMR-deficient tumors, but criteria to select individuals in whom tumor MMR testing should be performed are unclear.(More)
BACKGROUND A diet high in red meat is an established colorectal cancer (CRC) risk factor. Carcinogens generated during meat cooking have been implicated as causal agents and can induce oxidative DNA damage, which elicits repair by the base excision repair (BER) pathway. METHODS Using a family-based study, we investigated the role of polymorphisms in 4 BER(More)
BACKGROUND & AIMS Outcomes of colon surveillance after colorectal cancer screening with colonoscopy are uncertain. We conducted a prospective study to measure incidence of advanced neoplasia in patients within 5.5 years of screening colonoscopy. METHODS Three thousand one hundred twenty-one asymptomatic subjects, age 50 to 75 years, had screening(More)
Some serrated polyps of the colorectum are likely preinvasive lesions, evolving through a newly recognized serrated pathway to colorectal cancer. To assess possible risk and protective factors for serrated polyps and particularly to explore differences in risk factors between polyps in the right and left colorectum, we pooled data from three large(More)