Can serial PET/CT imaging during and after chemoradiation treatment assist in individualizing therapy for patients with squamous cell cancer of the head and neck?

Abstract

e17022 Background: PET/CT imaging with FDG has the potential advantage over conventional imaging of demonstrating metabolic changes in tumors early in the course of chemoradiation which may aid in individualization of therapy for patients. Methods: Sixteen patients with stage III/IV head and neck cancer were prospectively entered on a study to evaluate the role of PET/CT between March 2006 and July 2007. Enrolled patients were treated with chemoradiation (CRT) and had a series of 5 PET/CT scans in the treatment position at the initiation of therapy, 2 and 4 weeks after initiation of chemoradiation and then 6 weeks and 3 months after completion of treatment. The max standard uptake values (SUV) were recorded in the primary tumors. In addition CT imaging was examined and the maximum dimensions of the primary tumor were recorded. Results: Three patients have recurred at the primary site and follow-up ranges from 15–30 months. Twelve patients had decreasing SUV 2 weeks after initiation of CRT, one stayed the same, and two increased. The change ranged from a 75% decrease to a 21% increase compared to the initial scan. All patients had stable or decreasing SUV 4 and 6 weeks after initiation of therapy (range: 0 to 100% decrease). The change in SUV at 2 weeks, 4 weeks, post RT 6 weeks and 3 months compared to baseline for the 3 patients with local recurrence and the 13 patients who remain disease free were -7%, -62%, -50%, and -16% compared to -34%, -62%, -77%, and -81%, respectively. Higher PET values were significantly associated with a higher risk of recurrence (p = 0.04). In contrast CT imaging demonstrated that tumor measurements at 2 weeks, 4 weeks, post RT 6 weeks, and 3 months steadily decreased in both groups with mean changes in the recurrence group and in the locally controlled group of -11%, -46%, -77%, and -100% and -47%, -57%, -73%, and -99%, respectively. CT measurements were not associated with the risk of recurrence (p = 0.72). Conclusions: Changes in SUV from PET/CT were significantly predictive of tumor recurrence compared to CT imaging alone. If this observation can be verified in a larger cohort of patients, individualization of treatment based on PET/CT changes may be possible in order to improve outcomes for these patients. No significant financial relationships to disclose.