The diagnostic and prognostic utility of positron emission tomography/computed tomography-based follow-up after radiotherapy for head and neck cancer

BACKGROUND: The detection of subclinical head and neck cancer recurrence or a second primary tumor may improve survival. In the current study, the authors investigated the clinical value of a follow-up program incorporating serial ¹⁸F-fluorodeoxyglucose-positron emission tomography integrated with computed tomography (PET/CT) in the detection of recurrent disease in patients with head and neck cancer. METHODS: A total of 240 PET/CT scans were reviewed in 80 patients with head and neck cancer who were treated with radiotherapy (RT) from July, 2005 through August, 2007. All patients were followed with clinical examination, PET/CT, and correlative imaging for a minimum of 11 months (median follow-up, 21 months). RESULTS: The sensitivity, specificity, and positive and negative predictive values of PET/CT-based followup for detecting locoregional recurrence were 92%, 82%, 42%, and 98%, respectively. Corresponding values for distant metastases or second primary tumors were 93%, 96%, 81%, and 98%, respectively. Eight patients (10%) developed disease recurrences or second primary tumors that were amenable to salvage surgery with negative surgical margins. The 2-year progression-free survival and 2-year overall survival rates were significantly different between patients who had a negative and those with a positive PET/CT result within 6 months of the completion of RT (93% vs 30% [P<.001] and 100% vs 32% [P<.001], respectively). CONCLUSIONS: Although post-therapy follow-up using PET/CT is reportedly associated with a high false-positive rate in the irradiated head and neck, PET/CT appears to be a highly sensitive technique for the detection of recurrent disease. Furthermore, negative PET/CT results within 6 months of the completion of RT offer significant prognostic value.