Prognostic significance of tumor response as assessed by sequential ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography during concurrent chemoradiation therapy for cervical cancer

Purpose To investigate the prognostic role of metabolic response by the use of serial sets of positron emission tomography/computed tomography (PET/CT) in patients with cervical cancer who were treated with concurrent chemoradiation therapy (CCRT). Methods and Materials A total of 60 patients who were treated with CCRT between February 2009 and December 2010 were analyzed. Three sequential PET/CT images were acquired for each patient: pre-CCRT, during-CCRT at 4 weeks of CCRT, and 1 month post-CCRT PET/CT. Metabolic responses were assessed qualitatively. The percentage changes in the maximum values of standardized uptake value (ΔSUV_max%) from the PET/CT images acquired pre-CCRT and during-CCRT were calculated. Receiver operating characteristic (ROC) curve analysis was performed to evaluate whether ΔSUV_max% could predict complete response (CR) on the post-CCRT PET/CT and to identify the best cutoff value. Prognostic factors of progression-free survival (PFS) were analyzed. Results During-CCRT PET/CT showed that 8 patients (13%) had CR, and the other 52 patients (87%) had partial response (PR). On the post-CCRT PET/CT, 43 patients (73%) had CR, 12 patients (20%) had PR, and 4 patients (7%) had progressive disease. The average SUV _max in primary tumors was 16.3 (range, 6.4-53.0) on the pre-CCRT PET/CT images and 5.3 (range, 0-19.4) on the during-CCRT PET/CT images. According to ROC curve analysis, ΔSUV_max% could predict CR response on post-CCRT PET/CT (P<.001, cutoff value of 59.7%). In all patients, the PFS rate was 71.9% at 2 years. Multivariate analysis showed that ΔSUV_max% ≥60% (P=.045) and CR response on the post-CCRT PET/CT (P=.012) were statistically significant predictors of PFS. Conclusion Metabolic responses on the during-CCRT images at 4 weeks of treatment and 1-month post-CCRT PET/CT images may predict treatment outcomes in patients with cervical cancer. ΔSUV_max% ≥60% at 4 weeks of CCRT may predict CR response on 1-month post-CCRT PET/CT and also PFS.