Serial positron emission tomography scans following radiation therapy of patients with head and neck cancer

Background. A single institution study was undertaken to evaluate the role of positron emission tomography (PET) scans with fluorodeoxyglucose (FDG) p rior to radiation and following radiation. Methods. Forty-five patients with head and neck cancers were evaluated with FDG-PET scans as well as either CT or MRI prior to treatment with definiti ve radiation (RT). These same scans were obtained following completion of F IT at 1 month (36 patients), 4 months (28 patients), 12 months (19 patients ), and 24 months (15 patients). Standard uptake values (SUV) normalized for blood glucose and lean body mass were calculated on the initial and 1-mont h post-treatment PET scans. Results. Fifteen patients are alive without evidence of disease at 24 to 52 months following RT. Initial SUVs were calculated on the primary tumor sit e and ranged from 2.5 to 28.5. These values did not have any correlation wi th local control when examined for the entire group, primary site, or T sta ge. One-month post-RT SUV ranged from 1.8 to 6.24. Of the 36 1-month post-R T PET scans, six were interpreted as positive for residual disease and were confirmed by biopsy. Four of the five scans, which were interpreted as equ ivocal, were positive on biopsy. Seven of the 25 scans, which were interpre ted as negative for tumor, were positive on biopsy. Four-month scans were m ore accurate for disease with disease noted in 0 of 18 negative scans, 6 of 7 positive scans, and 2 of 3 equivocal scans. Conclusions. PET is useful for initial imaging of head and neck cancers. SU V does not appear to be useful for predicting outcome following treatment w ith RT One-month post-RT scans were inaccurate for predicting the presence of cancer. Four-month post-RT scans were a better predictor for the presenc e of cancer. (C) 2001 John Wiley & Sons, Inc.