PET/CT shows promise predicting outcomes in head, neck cancer

By Will Morton, AuntMinnie.com staff writer

July 23, 2021 -- PET/CT imaging may help predict outcomes in patients on immunotherapy for head and neck cancer, according to a research letter published July 23 in JAMA Otolaryngology -- Head and Neck Surgery.

A group of researchers explored levels of radiotracer uptake on F-18 FDG PET/CT in patients with head and neck squamous cell cancer (HNSCC) before and after they began treatment with immune checkpoint inhibitors. The team found that higher radiotracer uptake in tumors as measured by maximum standardized uptake values (SUVmax) was associated with poorer overall survival.

"SUVmax on PET-CT may provide clinically useful information when risk-stratifying patients receiving immune checkpoint inhibitors for head and neck cancer," wrote the authors, led by research fellow Dr. Conall Fitzgerald of Memorial Sloan Kettering Cancer Center in New York City.

Approximately 66,000 people develop head and neck cancer annually, and 14,600 die from the disease, with a significantly higher death rate in men than women. Identifying clinical, laboratory, or genomic biomarkers to predict response to the disease is an important goal, the authors wrote.

A previous study in 2014 suggested SUVmax on PET/CT may predict outcomes in patients with HNSCC. University of Washington researchers found patients in a group of 44 who had a higher mean SUVmax of 9 experienced poorer outcomes.

In this study, the investigators reviewed imaging from 98 patients treated with immune checkpoint inhibitors between 2013 and 2018. The mean age of patients was 62.2 years, and 77 were men. Patients who received PET-CT imaging within 180 days prior to starting treatment were included.

The SUVmax was categorized as above or below the median, which in these patients was 11. Primary outcomes were overall survival and progression-free survival. Patients were followed for two years.

SUVmax above the median was associated with poorer overall survival (hazard ratio, 1.65), the authors found. The association was similar when analyzing SUVmax as a continuous variable (hazard ratio, 1.05).

The association between high SUVmax and poorer overall survival also remained significant when adjusted for Eastern Cooperative Oncology Group performance status (hazard ratio, 1.63). SUVmax was not associated with progression-free survival (hazard ratio, 0.92).

"In patients treated with [immune checkpoint inhibitors] for recurrent or metastatic HNSCC, high SUVmax was associated with poorer prognosis," the authors wrote.

The authors pointed out an important limitation -- that several other factors can influence SUVmax, such as lean body mass, blood glucose level, and postinjection uptake time, meaning image interpretation must be taken in context for each patient. Other factors can also influence survival, including overall burden of comorbid illness.

Ultimately, though, few biomarkers predictive of response to immune checkpoint inhibitor drugs have been described in patients with HNSCC. Therefore, the study helps open a window for imaging tests to provide useful prognostic information, the authors suggested.

"Additional research, including advanced radiomic technologies, may provide insights to allow clinicians to more effectively predict response to [immune checkpoint inhibitor] therapy based on radiologic findings," Fitzgerald et al concluded.


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