Mark Dewhirst, “The Human Synapse,” Eases Into Retirement

May 9, 2017
By: Julie Poucher Harbin, Writer, DCI

TOP: Yearbook photo from Colorado State University BOTTOM RIGHT: Mark Dewhirst, DVM, PhD, (far right) administers radiotherapy to Jalopy, a tortoise from the Staten Island Zoo suffering from sarcoma. “We used the tire from my son’s tire swing to immobilize him after we had placed him into a cold room to slow him down, since reptiles cannot maintain their own body temperature," said Dewhirst. "You can see the gantry of the linear accelerator, which was rotated around so that we could treat the tumor from several angles.” When a Galapagos tortoise suffering from sarcoma needed help in 1983, zookeepers at the Staten Island Zoo called Mark Dewhirst, DVM, PhD, a young scientist at University of Arizona who had been conducting clinical trials on dogs using radiotherapy.

They were hoping radiotherapy might also help the tortoise — named Jalopy because he scooted around with the aid of a skateboard contraption after losing mobility from his many surgeries — so they shipped him Dewhirst’s way.  

Dewhirst’s ingenuity in rigging up a system to treat the 80-year-old tortoise, a species he’d never treated before, lengthened the tortoise’s life and made headlines.

The grandson of farmers and the son of a science professor at University of Arizona who studied parasites in cattle, Dewhirst said he grew up around animals, first in Kansas and then in Arizona. He seemed to be destined for veterinary medicine.

After earning an undergraduate degree in chemistry from University of Arizona and doctorates in veterinary medicine (1975) and radiation biology (1979) from Colorado State University, he joined the faculty at University of Arizona. His research career spanned more than three decades, most of them at Duke.

Come the end of the semester, Dewhirst — now vice director for basic science at Duke Cancer Institute and professor of radiation oncology, biomedical engineering and pathology — says he’s hanging up his lab coat.

The Dewhirst Lab, which focuses on the tumor microenvironment, specifically as it relates to tumor metabolism and hypoxia and ways to improve treatment modalities, including hyperthermia, is shutting down.

Mark Dewhirst, DVM, PhD, with Benjamin Moeller, MD, PhD, and John Kirkpatrick, MD, PhD. (2004) Moeller was Dewhirst’s PhD student (MSTP Program) and Kirkpatrick (center) was a resident in radiation oncology at the time. Kirkpatrick remained at Duke and focuses primarily on radiotherapy for brain tumors. Moeller did a residency in radiation oncology at MD Anderson Cancer Center and is now in private practice in Charlotte.Dewhirst, who turns 68 this month, and radiation oncologist James Oleson, MD, now retired, were recruited to Duke in 1984 from the University of Arizona for their work in hyperthermia, a cancer treatment whereby body tissue is exposed to high temperatures and cancer cells are sensitized to radiation and chemotherapy or killed.

At the time, Dewhirst was also being recruited by Colorado State University and by the University of Wisconsin.

“It only took one trip for me to realize what a special place Duke is, and I do not regret that decision one bit,” he said. “Particularly impactful for me was the radiologic imaging capabilities here. Charlie Putman, PhD, who was chairman of the radiology department, was fantastic. I thought ‘we are coming here to start a hyperthermia program and we will have the capability of doing really important work with imaging that can interface with that’.”