PET and recurrent squamous cell carcinoma of the head and neck: a surgeon's view.

In this issue of the American Journal of Neuroradiology, Fischbein et al (page 1189) review their findings of 35 patients evaluated with PET scans after definitive treatment for squamous cell carcinoma of the upper aerodigestive tract. The data of this retrospective study support their postulate that PET scanning after the administration of 2-fluoro-2-deoxy-Dglucose (FDG) is sensitive but not specific for the detection of recurrent cancer, and that a negative FDG PET scan reliably excludes recurrent disease. How important is this information to the patients who are fighting this cancer and the clinicians who care for them? This study suggests that a negative scan should be reassuring in a patient who is troubled by symptoms that might suggest recurrent tumor. But it is not clear how commonly this occurs, because not all study patients are symptomatic. The more critical and challenging issue is the ability of this imaging procedure to distinguish between recurrent cancer and treatment-related inflamation or fibrosis in patients who become symptomatic or who develop a mass during follow up after definitive cancer therapy. The authors begin with the generally accepted bias that FDG PET is not good at distinguishing inflamation from tumor, and the study design is focused on the procedure, rather than on a specific clinical issue. A prospective study of the value of FDG PET in a group of patients presenting with the above clinical problem (rather than a retrospective study of a group of patients who had the procedure done for various reasons at various times after treatment), might provide information of more use to treating physicians. The strong negative predictive value identified for this imaging procedure does complement the value of