Association of post-treatment positron emission tomography with locoregional control and survival after radiation therapy for squamous cell carcinoma of the vulva.

Abstract

The aim of this study was to investigate the use of post-treatment F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for vulvar cancer and compare metabolic response to clinical outcomes. This retrospective study included 21 patients with vulvar squamous cell carcinoma treated with curative-intent radiation between 2007 and 2015. All patients received intensity-modulated radiation treatment (IMRT), a pre-treatment FDG/PET-CT, and a post-treatment FDG-PET/CT performed at a median time of 3months post-IMRT. Median follow-up time was 28months. Post-treatment FDG-PET/CT demonstrated no evidence of disease (NED) in 12 patients and residual or progressive disease (PD) in 9. FDG-PET/CT response significantly correlated with biopsy-proven locoregional failure (p=0.02) and was the only significant factor associated with overall survival (OS) (p=0.049). Patients with NED on FDG-PET had a 2-year locoregional control (LRC) of 89% versus 25% for those with PD (p<0.01). Patients with NED on FDG-PET/CT had a 2-year OS of 100% versus 42% for those with PD (p=0.02). FDG-PET/CT evaluation had a sensitivity of 100% and a specificity of 71% for detecting pathologically proven residual disease in patients receiving neoadjuvant or definitive radiation. In this single-institution study of women with vulvar cancer, post-treatment response on FDG-PET/CT was associated with LRC and OS.