Prognosticating Factors in PET CT and MRI of Cervical Cancer Treated With Chemoradiotherapy

We aim to evaluate the functional and anatomical imaging characteristics of locally advanced cervical cancer (LACC) to identify potential prognosticating imaging biomarkers in the context of chemoradiotherapy treatment (CRT).

This retrospective review analysed patient data over a period of seven years. Patients with locally advanced cervical cancer who have undergone FDG PET CT and MRI were identified through Report Analytics. Patients with LACC who have undergone chemoradiotherapy were identified through review of the electronic records. Pre and post-treatment imaging were analysed and compared. The patients were dichotomised into complete metabolic responders (CMR) and non-complete metabolic responders (N-CMR) as per European Organisation for Research and Treatment of Cancer (EORTC) criteria. Imaging parameters in PET CT and MRI including SUV max, SUV mean, total lesion glycolysis (TLG), lesion metabolic tumour volume (MTV), apparent diffusion coefficient (ADC) minimum were examined. Kaplan-Meier analysis was used to evaluate differences in overall survival (OS) and disease-free survival (DFS) between the CMR and N-CMR groups. Pearson's correlation and Fischer's exact test were used to evaluate the potential prognosticating value of the PET CT and MRI imaging parameters as predictors of metabolic response to CRT.

A total of 159 FDG PET CT scans were conducted in the 7-year period, of which there were 61 individual patients identified for inclusion into the present study. The average imaging follow-up for the patients included between 2019 and 2024 was 63.3 months, and chemoradiotherapy follow-up was 62.9 months. The patients were dichotomized into CMR and N-CMR groups. There is a statistically significant difference in overall survival, with 1 mortality (5%) in the CMR group vs. 19 mortality (70%) in the N-CMR group (p = 0.0001). However, no statistically significant difference in follow-up 87.1 months vs. 57.1 months (p = 0.20). In the overall cervical cancer cohort as well as the squamous cell carcinoma subgroup (n = 32), the comparison of CMR and N-CMR groups revealed a statistically significant difference in the following FDG PET imaging parameters: SUV max, SUV mean, ADC minimum and MTV. The CMR group has tumours with higher SUV max and SUV mean (difference of 7.5 and 5.1 respectively) and smaller MTV (difference of 20.1 cm³). However, there was no demonstrable difference in TLG and MRI ADC min values between the dichotomized groups. The tumoral SUV max and ADC min were weakly negatively correlated. There was no statistically significant difference in International Federation of Gynaecology and Obstetrics (FIGO) stage of disease (individual stage and IIB or higher) and pathological grade in the dichotomized groups.

This retrospective analysis identified functional imaging predictors of positive response to CRT in LACC patients using FDG PET CT. Furthermore, this confirms the negative correlation between functional and anatomical imaging parameters, albeit non-statistically significant (namely SUV max and ADC min). The present results indicated cervical cancer with higher SUV values (max and mean) and smaller MTV were more likely to respond to CRT. There is no demonstrable difference in pathological grading and FIGO stage of disease. Prospective studies in larger cohorts are indicated to ascertain the predictive value of functional and anatomical imaging parameters and their correlation with tumour histopathological features.