Dr. Dennis Ahnen, M.D.
Professor of Medicine
Colon cancer
Dr. Dennis Ahnen is a Professor of Medicine and has been on the faculty of the University of Colorado Denver School of Medicine since 1982. His research interest is in understanding the process of colorectal cancer and its prevention. His laboratory conducts both basic and clinical investigations related to this issue. At the basic level Dr. Ahnen's laboratory is examining the biologic and the biochemical mechanisms of the chemopreventive effects of the non-steroidal anti-inflammatory drugs (NSAIDs). Dr. Ahnen's laboratory was one of the first to demonstrate that NSAIDs induce apoptotic cell death as well as cause cell cycle arrest and his laboratory showed that this effect could be induced by metabolites of NSAIDs that did not inhibit cyclooxygenases suggesting that there were other biochemical targets for these drugs, one of which is a subclass of cGMP phosphodiesterases and another is inhibition of EGF receptor signaling. Current studies are designed to identify the multiple biochemical targets of the NSAIDs on cell lines and in vivo. Pam Rice PhD is a co-investigator with Dr. Ahnen in the laboratory and is central to the basic science work.
Dr. Ahnen's laboratory also is active in clinical and behavioral studies of colon cancer prevention. The laboratory has conducted clinical trials of screening colonoscopy, stool DNA testing, and adenoma prevention trials with non-steroidal anti-inflammatory drugs, folate supplementation and calcium and is currently conducting adenoma prevention trials testing selenium, Vitamin D and Calcium and DFMO as chemopreventive agents. In collaboration with Dr. Al Marcus, Dr. Ahnen conducts behavioral trials designed to improve colorectal cancer screening rates. These clinical trials provide populations for students not only to learn the basic tenants of epidemiology and clinical trial design/conduct but also provide a source of material for biomarker studies. In collaboration with Dr. Jan Lowery, Dr. Ahnen directs two Cancer Registries that identify families with clustering of colorectal cancer. These families are valuable resources for studies to identify cancer predisposition genes and for prevention trials. The extensive experience and broad expertise found in Dr. Ahnen's laboratory group can provide a strong environment for research training of graduate students.
Selected Recent Publications
Wold KS, Byers T, Crane LA, Ahnen DJ. What do cancer survivors believe causes cancer? Cancer Causes and Control, 16:115-23, 2005.
Iwamoto M, Hoffenberg EJ, Carethers JM, Doctolero R, Tajima A, Sugano K, Franklin WA, Ahnen DJ. Nuclear Accumulation of ?-Catenin Occurs Commonly in the Epithelial Cells of Juvenile Polyps. Pediatric Research, Pediatr Res. 57:4-9, 2005.
Robertson DR, Greenberg ER, Beach M, Sandler RS, Ahnen DJ, Haile RW, Burke CA, Snover DC, Bresalier RS, McKeown-Eyssen G, Mandel JS, Bond JH, van Stolk RU, Summers RW, Rothstein R, Church TR, Cole B, Byers T, Mott L, Baron JA. Colorectal Cancer in Patients Under Close Colonoscopic Surveillance. Gastroenterology 129:34-41, 2005.
Limburg PJ, Wei W, Ahnen DJ, Qiao Y, Hawk ET, Wang G, Giffen CA, Wang G, Roth MJ, Lu N, Korn EL, Ma Y, Caldwell KL, Dong Z, Taylor PR and Dawsey SM. Randomized, Placebo-Controlled, Esophageal Squamous Cell Cancer Chemoprevention Trial of Selenomethionine and Celecoxib. Gastroenterology 129:863-73, 2005.
Denberg TD, Melhado TV, Coombes JM, Beaty BL, Berman K, Byers TE, Marcus AC, Steiner JF, Ahnen DJ. Predictors of non-adherence to screening colonoscopy. J Gen Int Med, 20:989-95, 2005.
Pangburn HA, Kraus H, Ahnen DJ, Rice PL. Sulindac metabolites inhibit epidermal growth factor receptor activation and expression. J Carcinog. 4:16-24, 2005.
Rice PL, Peters S, Beard KS, Ahnen DJ. Sulindac Independently Modulates Extracellular Signal-regulated Kinase 1/2 and Cyclic GMP-dependent Protein Kinase Signaling Pathways. Mol Cancer Ther. 5:746-54, 2006.
Barry EL, Baron JA, Bhat S, Grau MV, Burke CA, Sandler RS, Ahnen DJ, Haile RW, O'Brien TG. Ornithine decarboxylase polymorphism modification of response to aspirin treatment for colorectal adenoma prevention. J Natl Cancer Inst. 98:1494-500, 2006.
Levine JS, Ahnen DJ. Clinical practice. Adenomatous polyps of the colon. N Engl J Med. 355:2551-7, 2006.
Einspahr JG, Martinez ME, Jiang R, Hsu CH, Bhattacharrya AK, Ahnen DJ, Jacobs ET, Houlihan PS, Webb CR, Alberts DS, Hamilton SR. Associations of Ki-ras proto-oncogene mutation and p53 gene overexpression in sporadic colorectal adenomas with demographic and clinicopathologic characteristics. Cancer Epidemiol Biomarkers Prev. 15:1443-50, 2006.
Denberg TD, Coombes JM, Byers TE, Marcus AC, Feinberg LE, Steiner JF, Ahnen DJ. Effect of a mailed brochure on appointment-keeping for screening colonoscopy: a randomized trial. Ann Intern Med. 145:895-900, 2006.
Cole BF, Baron JA,. Sandler RS, Haile RW, Ahnen DJ, Bresalier RS, McKeown-Eyssen G, Summers RW, Rothstein RI, Burke CA, Snover DC, Church TR, Allen JI, Robertson DJ, Beck GJ, Bond JH, Byers T, Mandel JS, Mott LA, Pearson LH, Barry EL, Rees JR, Marcon N, Saibil F, Ueland PM, Greenberg ER, For the Polyp Prevention Study Group. A Randomized Trial of Folic Acid for the Prevention of Colorectal Adenomas. JAMA 297:2351-9, 2007.
Lieberman DA, Weiss DG, Harford WV, Ahnen DJ, Provenzale D, Sontag SJ, Schnell TG, Chejfec G, Campbell DR, Kidao J, Bond JH, Nelson DB, Triadafilopoulos G, Ramirez FC, Collins JF, Johnston TK, Mcquaid KR, Garewal H, Sampliner RE, Esquivel R, Robertson D. Five-year colon surveillance after screening colonoscopy. Gastroenterology 133:1077-85, 2007.
Ahnen DJ, Guerciolini R, Hauptman J, Blotner S, Woods CJ, Whittington J, Wargovich MJ. Effect of orlistat on fecal fat, fecal biliary acids and colonic cell proliferation in obese subjects. Clinical Gastroenterology and Hepatology 5:1291-9, 2007.
O'Dwyer PJ, Eckhardt SG, Haller DG, Tepper J, Ahnen D, Hamilton S, Benson AB 3rd, Rothenberg M, Petrelli N, Lenz HJ, Diasio R, DuBois R, Sargent D, Sloan J, Johnson CD, Comis RL, O'Connell MJ; Gastrointestinal Scientific Leadership Council of the Coalition of Cancer Cooperative Groups. Priorities in colorectal cancer research: recommendations from the Gastrointestinal Scientific Leadership Council of the Coalition of Cancer Cooperative Groups. J Clin Oncol. 25:2313-21, 2007.
Debourcy AC, Lichtenberger S, Felton S, Butterfield KT, Ahnen DJ, Denberg TD. Community-based Preferences for Stool Cards versus Colonoscopy in Colorectal Cancer Screening. J Gen Intern Med. 23:169-74, 2008.
Meyskens FL, McLaren CE, Pelot D, Fujikawa-Brooks S, Carpenter PM, Hawk E, Kelloff G, Lawson MJ, Kidao J, McCracken J, Albers CG, Ahnen DJ, Turgeon DK, Goldschmid S, Lance P, Hagedorn CH, Gillen DL, Gerner EW. Difluoromethylornithine Plus Sulindac for the Prevention of Sporadic Colorectal Adenomas: A Randomized Placebo-Controlled, Double-Blind Trial. Cancer Prevention Research 1:9-11, 2008.
Figueiredo JC, Levine AJ, Grau MV, Barry EL, Ueland PM, Ahnen DJ, Byers T, Bresalier RS, Summers RW, Bond J, McKeown-Eyssen GE, Sandler RS, Haile RW, Baron JA. Colorectal adenomas in a randomized folate trial: the role of baseline dietary and circulating folate levels. Cancer Epidemiol Biomarkers Prev. 17:2625-31, 2008.
Levine AJ, Wallace K, Tsang S, Haile RW, Saibil F, Ahnen D, Cole BF, Barry EL, Munroe DJ, Ali IU, Ueland P, Baron JA. MTHFR genotype and colorectal adenoma recurrence: data from a double blind placebo controlled clinical trial. In press, Cancer Epi Biomarkers Prev Cancer Epidemiol Biomarkers 17:2409-15, 2008.
Groff R, Nash R, Ahnen DJ. Clinical significance of serrated polyps of the colon. Current Gastroenterology Reports10:490-8, 2008.
Messersmith WA, Ahnen DJ. Targeting EGFR in Colorectal Cancer. New Engl J Med 359:1834-6, 2008.
Ahlquist DA, Sargent DJ, Loprinzi CL, Levin TR, Rex DK, Ahnen DJ, Knigge K, M. Lance MP, Burgart LJ, Hamilton SR,Allison JE,Lawson MJ, Devens ME, Harrington JJ, Hillman SL. Stool DNA and Occult Blood Testing for Screen-detection of Colorectal Neoplasia: A Prospective Multi-center Comparison. Ann Intern Med;149:441-450, 2008.
Robertson DJ, Sandler RS, Ahnen DJ, Greeberg ER, Mott LA, Cole BF, Baron JA. Gastrin, Helicobacter pylori and Colorectal Adenomas. In press Clinical Gastroenterology and Hepatology, 2008.
Zou H, Taylor WR, Harrington JJ, Hussain FT, Cao X, Loprinzi CL, Levine TR, Rex DK, Ahnen D, Knigge KL, Lance P, Jiang X, Smith DI, Ahlquist DA. High Detection Rates of Colorectal Neoplasia by Stool DNA Testing With a Novel Digital Melt Curve Assay. In press Gasteroenterology 2008.
