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Clinical input can be key when interpreting head, neck cancer scans
Study suggests unnecessary biopsies can be greatly reduced
There is new evidence that a multidisciplinary approach to interpreting positron emission tomography/CT (PET/CT) scans can go a long ways toward eliminating unnecessary biopsies in patients with head and neck cancers. That's the gist of findings presented at the recent International Conference on Head and Neck Cancer.
The research, lead by Mark Varvares, MD, chair of otolaryngology — head and neck surgery at Saint Louis (MO) University, is significant because biopsies are particularly troublesome in patients with head and neck cancers. Clinicians have to be extremely careful with needle placement, and there is always the risk that such procedures inadvertently will cause the cancer to spread. Consequently, improving the accuracy of PET/CT scans can pay important dividends, Varvares emphasizes.
"These biopsies have to be done under general anesthesia, there are risks to the airway when you take head and neck cancer patients who have been treated with radiation therapy in for a biopsy, and there is a risk of developing radionecrosis in a patient who has had previous high dose radiotherapy," he says. "A biopsy could set up a non-healing situation that could actually lead to severe injury to the organ, requiring even something as drastic as a laryngectomy."
Varvares suggests that unnecessary biopsies can be significantly reduced simply by ensuring that the treating physician and the nuclear physician have an opportunity to review the patient's PET/CT scan, preferably at the same time, so that important clinical information is taken into account in their interpretation of the scan. His recommendation is based on analysis of 180 head and neck cancer patients who underwent PET/CT scans before and after treatment.
Investigators compared the incidence of false-positive findings of the PET/CT scans when they were evaluated by just a nuclear physician versus evaluation by a nuclear physician and a treating physician. Without input from the treating physician, the PET/CT scans produced a false positive rate of 50% and a false negative rate of 6%. However, when the treating physician and the nuclear physician evaluated the scans, the false-positive rate dropped to 11%, and the false-negative rate dropped to 3%.
"The way we validated our clinical impression in the vast majority of these patients is that we had subsequent scans done on the patients who had false-positives, but a negative clinical exam," says Varvares. "On the subsequent scans, either the uptake on PET went away completely, or it diminished over time with serial scans, pointing to it being an inflammatory process [rather] than disease progression."
Tumor boards facilitate interaction
Some medical centers already have formalized processes that are designed to promote the type of multidisciplinary interaction that Varvares describes. Consider David Townsend, PhD, who was involved with the development of the first PET/CT system and is the director of the molecular imaging and translational research program at the University of Tennessee Graduate School of Medicine in Knoxville. Townsend attends a head and neck tumor board on the third Monday of every month, where PET/CT scans are reviewed and cases are discussed with input from radiology, nuclear medicine, surgery, and pathology.
"If, in reviewing the PET/CT scan, there is some anomaly, and it turns out that the patient has some infectious condition or something that the nuclear medicine person might not know about, this will come out in the discussion," notes Townsend. "There is some ambiguity in reading these studies, and that clinical input, or even the surgeon's input if he has performed surgery, can be helpful in reading the PET/CT."
While most academic medical centers have these types of multidisciplinary discussions, they are not commonplace or, in some cases, even practical in community settings. However, Varvares maintains that physicians should make time for this kind of consultation. "If we can truly improve accuracy, then it is worth doing. It all has to do with where you practice and how you practice," he says. "It only takes a few minutes to look at a PET/CT scan."