The role of 18 F-FDG-PET/CT in predicting the histopathological response in locally advanced cervical carcinoma treated by chemo-radiotherapy followed by radical surgery: a prospective study.

Purpose: This prospective study aimed to evaluate whether ¹⁸ F-FDG-PET/CT performed before, during and after neoadjuvant chemo-radiotherapy (CRT) could predict histopathological response in patients with locally advanced cervical cancer (LACC) treated with CRT followed by radical surgery.
Methods: Between October 2010 and June 2014, 88 patients with LACC were enrolled. For each patient, three ¹⁸ F-FDG-PET/CT scans (baseline, early and final) were acquired and evaluated by qualitative and quantitative analysis. Maximum standardized uptake value (SUV _max ), SUV _mean , metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured as absolute values and their percentage variation (delta) (early vs. baseline and final vs. baseline). The role of ¹⁸ F-FDG-PET/CT in predicting lymph node (LN) residual disease was evaluated by qualitative analysis only. Histopathology was the reference standard.
Results: At histopathology, 40 patients had complete response (CR, pR0), 48 had partial response (PR: 21 microscopic [pR1] and 27 macroscopic [pR2]). At baseline, SUV _max and SUV _mean were significantly higher in pR0 than in pR1-pR2 patients. At early evaluation, MTV and TLG were significantly higher in pR1-pR2 than in pR0 patients. At final evaluation, SUV _max , SUV _mean and TLG were significantly higher in pR1-pR2 than in pR0 patients. Delta SUV parameters and delta TLG were significantly lower in PR group both during and after CRT. Delta MTV was significantly lower in patients with PR in the early phase only. In receiver operating characteristic (ROC) curve analysis, baseline SUV _mean , early delta TLG, and final delta SUV _max better discriminated PR, providing 83.3%, 67.6% and 85% positive predictive value (PPV) and 60.3%, 90% and 70.8% negative predictive value (NPV), respectively. For LN assessment, high NPV was observed at early and final ¹⁸ F-FDG-PET/CT (93.5% and 92.3%, respectively).
Conclusion: In LACC patients treated with CRT followed by surgery, early variations in metabolic parameters effectively discriminate histopathological PR of the primary tumor, suggesting the potential role of ¹⁸ F-FDG-PET/CT in early personalized treatment. The high NPV of early and final PET/CT could enable "tailored surgery" by avoiding lymphadenectomy in selected patients.