FDG-PET/CT-based treatment response predicts recurrence and overall survival in locally advanced cervical cancer

BACKGROUND: [18 F]-fluorodeoxyglucose (FDG) positron emission tomography combined with computed tomography (PET-CT) is used for staging and treatment response evaluation in patients with locally advanced cervical cancer. While the maximum standardised uptake value (SUVmax) is a commonly used PET parameter, volume-based parameters (metabolic tumour volume (MTV) and total lesion glycolysis (TLG)) may offer superior predictive value. This study aimed to investigate the predictive value of different treatment response outcomes assessed with PET-CT, using both standard and volume-based PET parameters. METHODS: We retrospectively analyzed 133 patients with locally advanced cervical cancer treated with (chemo)radiotherapy who underwent PET-CT pre- and post-treatment. SUVmax, MTV and TLG were semi-automatically extracted from all scans, including tumour, lymph nodes and metastases. Treatment response was classified as complete metabolic response (CMR) (complete resolution of FDG uptake in all lesions), partial metabolic response (PMR) (> 25% reduction of SUVmax/MTV/TLG), progressive metabolic disease (PMD) (> 25% increase of SUVmax/MTV/TLG or appearance of new FDG-avid lesions) or stable disease (SD) (does not qualify for CMR, PMR or PMD). The three PET-parameters were analysed separately. PMR and SD were analysed as one group due to limited number of events. Associations between treatment response and overall survival (OS) as well as recurrence (binary variable) were analysed through Cox and logistic regression models, respectively. RESULTS: For recurrence (binary variable), the odds ratio (OR) was 1.2 for patients with PMR/SD for SUVmax, MTV and TLG, while in the group of patients with PMD, it was 1.7 for SUVmax and 1.8 for MTV and TLG, using CMR as reference (i.e. for CMR, the OR is 1.0). The hazard ratio (HR) for OS was 4.0 for patients with PMR/SD and 16.0 for those with PMD, based on SUVmax; for MTV and TLG, HRs were 2.9 for patients with PMR/SD and 16.0 for those with PMD, using CMR as reference (HR 1.0). C-index from adjusted Cox models were comparable: 0.84 for SUVmax, and 0.86 for both MTV and TLG. CONCLUSION: FDG-PET/CT-based assessment of treatment response is a strong predictor of recurrence and overall survival in locally advanced cervical cancer. SUVmax, MTV, and TLG demonstrated similar predictive performance.