• CGA-IGC

Remembering Dennis Ahnen, MD (November,1946–August,2020)






Dr Swati Patel, CGA-IGC president, took the opportunity at the recent 2022 InSiGHT meeting to honour the memory of Dr Dennis Ahnen, an incredible husband, father, scientist, clinician, and mentor who sadly passed away in August 2020.




Dr Ahnen was taken from us far too soon, his life cut short; but it was a life, lived to the fullest at all levels.


Born in Wakefield, MI to a family rooted in the Air Force, he grew up as a global citizen but was All-American when it came to baseball, playing the game he loved right up to the ‘old guys’ league. He married his childhood sweetheart Carol and together they had 3 wonderful daughters and were blessed with 7 grandchildren.


Dr Ahnen completed his chief residency at the Detroit medical center and was recruited to University of Colorado for his GI Fellowship learning about research from Drs Fred Kern and Bill Brown.


It was here where his lifelong passion for colorectal cancer prevention was ignited. For one of their studies they needed controls without cancer and so he received a colonoscopy from Dr Brown where it was discovered that at aged 33, had a 2- cm rectal polyp with high-grade dysplasia. He credited Dr Brown with saving his “behind” and from then considered himself a “previvor”.


He spent some time at Stanford but was recruited back to the University of Colorado and built a lab at the Denver Veterans Affairs (VA) medical center. The Ahnen lab became the biomarker laboratory for a variety of multi-center chemoprevention trials, leading to many fruitful collaborations including with Dr John Baron’s Polyp Prevention Study Group and the Colon Cancer Family Registry, which published practice-changing work on how to improve the recognition and management of hereditary cancer patients.


Other notable contributions during his career were as a planning and executive committee member of the VA cooperative study 380, working closely to design the first large screening colonoscopy trial with the aim of identifying risk factors for advanced neoplasia. Later with the VA Cooperative study 573 (CONFIRM) comparing fecal immunochemical testing and colonoscopy for colorectal cancer screening. Dr Ahnen’s work during his important research career was supported by VA Merit Awards and the National Cancer Institute.


He was able to transfer his research knowledge to the bedside and to the benefit of the local community. He spearheaded operationalizing colorectal cancer screening as part of routine care for veterans. Because of his vision and leadership, the Denver VA exceeded the national “80% screened by 2018” by 2016, a goal that the rest of the state is still striving toward. He volunteered his time to establish the Hereditary Cancer Center at the University of Colorado and built a multidisciplinary center that is now thriving and serves patients from all over the state.


He served the Colorectal cancer community selflessly through his volunteer contributions to organizations such as Colorado Cancer Prevention Program, the American Cancer Society, the National Colorectal Cancer Roundtable, FightCRC, and the Colorectal Cancer Alliance.


In addition, he lobbied politicians and testified in front of legislative bodies. He developed tangible toolkits and resources for medical providers around early detection, he spoke at educational conferences to improve awareness and action around colorectal cancer screening.


His professional accomplishments and service have resulted in the most prestigious awards in our field including the Lifetime Achievement Award from the Collaborative Group of the Americas on Inherited Gastrointestinal Cancers (CGA-IGC) in 2018 and in 2020 the American Gastroenterological Association (AGA) William Beaumont Prize and the National Colorectal Roundtable Distinguished Lifetime Achievement Award.


While no-one will ever forget his incredible contributions to research, education and advocacy, he has left another lasting legacy. A legacy most cherished is the selfless mentorship he provided. He has molded generations of physicians, scientists, nurses, and genetic counselors who carry his torch of clinical excellence, scientific rigor, and humanism. His mentees most consistently comment on the aspirational example that Dr Ahnen has set for promoting collaboration, investing in mentorship and elevating unheard voices. This is the .Dennis Ahnen Word Cloud. This word cloud was constructed from sentiments about Dennis, shared by colleagues, collaborators, friends, and mentees from around the world.


JOYFUL, ZEST FOR LIFE, KIND AND HUMBLE. HE WAS BALANCED and he had SWAG. HE SET THE STANDARD. We know this from his scientific contributions, but even in fashion and is credited as the first to popularize the selfie.


He kept his positivity despite everything that was thrown at him. Amid treatment for an advanced stage appendiceal cancer and a global pandemic, he still found the energy and satisfaction from making us all laugh.

He lived life to the fullest. You can see here a beautiful renewal of vows 50 years into marriage, officiated by the stylish Dr Macrae.


CGA-IGC is lucky to have benefited from Dr Ahnen's service to the organization. He was a dedicated council member, education committee member, and joyful fundraiser for CGA every year at the annual meeting raffles. We will miss him dearly, but will honor his memory by celebrating the CGA-IGC Dennis J. Ahnen Outstanding Service Award Recipient, Ms. Brandie Heald Leach. Join us at #CGAIGC22 to honor Dr Ahnen.

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