Cancer patients should not have to wait until treatment ends to find out if it has worked, says City of Hope radiation oncologist Khanh Nguyen, M.D. The way he sees it, the earlier physicians can see whether cancer is responding to therapy, the earlier they can adjust treatment to benefit patients.
The key might be medical imaging.
Nguyen, who joined the Division of Radiation Oncology in August, is doggedly pursuing the potential of imaging during treatment to determine whether radiation therapy or systemic treatments, such as chemotherapy, are successfully killing off cancer cells.
“I want to know if there is a way to predict, early on, whether treatments are effective or not, and whether there is a benefit to the patient to undergoing that treatment,” Nguyen said. “We may be able to gauge early treatment response using PET-CT.”
PET-CT draws on two imaging technologies, combining the power of positron emission tomography (PET) with the intricacy of computed tomography (CT). PET can show cancer’s metabolic activity, while CT displays the structures of a patient’s anatomy in detail. Over the last several years, researchers have begun exploring whether PET-CT can provide physicians never-before-seen information on treatment progress. The technique has potential for breast, esophageal, lung, rectal, anal and possibly pancreatic cancer. But much research needs to be done.
“We don’t know how early we can start using PET-CT to see if treatment is working,” Nguyen explained. “What’s the optimal timing? We need to understand how it relates to characteristics of the patient and type of tumor. The tumor grade, size, histology and other factors all might play a part.”
Ideally, if a PET-CT scan shows that patients are responding to their ongoing treatment, physicians can continue patients’ therapy with confidence.
But if the scan shows that the therapy is unlikely to help, physicians may recommend changing therapy early in the course of treatment — without losing time or putting patients through unnecessary discomfort.
He enthuses about PET-CT’s potential, and he knows the technology well. He moved to City of Hope from the University of Tennessee Medical Center, where he worked with David Townsend, Ph.D., co-inventor of PET-CT — dubbed the medical invention of the year 2000 by Time magazine.
Nguyen already has begun collaborating with other City of Hope physicians to include PET-CT in research protocols. Unfortunately, costs pose a challenge — the radioactive isotope for a single PET scan costs about $1,000 — but Nguyen is committed to pursuing funds to advance the research.
On the scientific side, Nguyen is seeking new markers that can be used with PET to detect cancer. Today’s commonly used isotope [F-18] fluorodeoxyglucose, or FDG, highlights tumors that metabolize glucose quickly, but some tumors, such as prostate cancers, do not do that. So he hopes to explore other isotopes that might spotlight hypoxia (oxygen deficiency), apoptosis (cellular suicide) and cellular proliferation, all important hallmarks of cancers.
He also is interested in the use of various imaging technologies, such as magnetic resonance imaging, for radiation targeting.
Nguyen earned his bachelor’s and master’s degrees in physics, cum laude, from Harvard University and his medical degree from the University of California, San Diego. He performed his residency in radiation oncology at Fox Chase Cancer Center.
David Townsend is scheduled to discuss PET-CT at City of Hope on Oct. 30. Please check upcoming calendars for more details.
