Roles of posttherapy ¹⁸F-FDG PET/CT in patients with advanced squamous cell carcinoma of the uterine cervix receiving concurrent chemoradiotherapy

Purpose: To assess the clinical roles of [¹⁸F]fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) performed 2-3 months after completion of concurrent chemoradiotherapy (CCRT), along with pretherapy characteristics, in patients with advanced squamous cell carcinoma of the uterine cervix enrolled in a prospective randomized clinical trial. Methods: Posttherapy PET/CT in patients with advanced FIGO stage or positive pelvic or para-aortic lymph node (PALN) defined on pretherapy PET/CT was classified as positive, equivocal, or negative. Overall survival (OS) rates between patients with different PET/CT results are compared. Pretherapy characteristics are examined for association with posttherapy PET/CT results and for prognostic significance in patients with equivocal or negative PET/CT. Results: PET/CT scans (n = 55) were positive, equivocal and negative in 9, 13 and 33 patients, respectively. All patients with positive scans were confirmed to have residual or metastatic disease and died despite salvage therapies. There is a significant OS difference between patients with positive and equivocal scans (P <.001) but not between patients with equivocal and negative scans (P =.411). Positive pretherapy PALN is associated with positive posttherapy PET/CT (P =.033) and predicts a poorer survival in patients with equivocal or negative posttherapy PET/CT (P <.001). Conclusions: Positive PET/CT 2-3 months posttherapy implies treatment failure and novel therapy is necessary to improve outcomes for such patients. A more intense posttherapy surveillance may be warranted in patients with positive pretherapy PALN.