Prognostic value of pretreatment ¹⁸F-FDG PET/CT and human papillomavirus type 16 testing in locally advanced oropharyngeal squamous cell carcinoma.

Abstract

Human papillomavirus type 16 (HPV-16) positivity is associated with favourable survival in oropharyngeal squamous cell carcinoma (OPSCC). We report here a study of the prognostic significance of (18)F-FDG PET/CT functional parameters and HPV-16 infection in OPSCC patients. We retrospectively analysed 60 patients with stage III or IV OPSCC who had had a pretherapy (18)F-FDG PET/CT scan and had completed concurrent chemoradiotherapy (n = 58) or curative radiotherapy (n = 2). All patients were followed up for ≥24 months or until death. We determined total lesion glycolysis (TLG) and the maximal standardized uptake values (SUV(max)) of the primary tumour and neck lymph nodes from the pretherapy (18)F-FDG PET/CT scan. Optimal cut-offs of the (18)F-FDG PET/CT parameters were obtained by receiver operating characteristic (ROC) curve analyses. Pretherapy tumour biopsies were studied by polymerase chain reaction to determine HPV infection status. The pretherapy tumour biopsies were positive for HPV-16 in 12 patients (20.0 %). Cox regression analyses revealed HPV-16 positivity and tumour TLG >135.3 g to be independently associated with overall survival (p = 0.027 and 0.011, respectively). However, only tumour TLG >135.3 g was independently associated with progression-free survival, disease-free survival and locoregional control (p = 0.011, 0.001 and 0.034, respectively). A scoring system was formulated to define distinct overall survival groups using tumour TLG and HPV-16 status. Patients positive for HPV-16 and with tumour TLG ≤135.3 g experienced better survival than those with tumour TLG >135.3 g and no HPV infection (p = 0.001). Tumour TLG was an independent predictor of survival in patients with locally advanced OPSCC. A scoring system was developed and may serve as a risk stratification strategy for guiding therapy.