Introduction

To evaluate the diagnostic accuracies of FDG PET/CT and morphological imaging(CT and MRI) in recurrent urothelial cancer (UC) after primary treatment.

Methods

Data of patients with recurrent UC after primary treatment were collected in a retrospective multicenter (San Raffaele Hospital, Milan; IOV–IRCCS, Padua; Hospital of Ferrara, Ferrara; Mayo Clinic, Rochester; University of Bologna) study. Inclusion criteria were: 1)patients with a known history of UC in the bladder and/or in the upper urinary tract (UTUC); 2)FDG PET/CT images after curative treatment of the primary tumor; 3)morphological imaging modalities (CT and MRI) performed before at least 3 months from PET/CT and 4)available standard of reference (e.g. histological data or imaging modalities) for the assessment of PET/CT findings. Exclusion criteria were other abdominal tumours and chemotherapy administration concomitant to imaging and non-urothelial cancer variants. Sensitivities, specificities, positive and negative predictive values were evaluated for all patients and separately for bladder and UTUC.

Results

Overall, 287 patients were included in the study. Two-hundred thirteen patients underwent cystectomy (74.2%), 35 nephoureterectomy (12.2%), 32 both cystectomy and nephoureterectomy (11.1%) and 7 other type of treatment for UTUC (endo-urology or segmental ureterectomy). Neoadjuvant and adjuvant treatments were performed in 36 (12,5%) and 111 (38,7%) patients, respectively. Sensitivity and specificity of PET/CT for the detection of recurrent UC were 94% (91%-96%) and 79% (68%-88%), respectively (Table 1). However, sensitivity was higher for bladder than UTUC cancer (95% vs. 85%) while specificity was lower in bladder cancer (78% vs. 85% for bladder and UTUC, respectively). The distribution of pathological FDG uptake was: 58 at local site, 126 at lymph nodes, 58 at skeletal site, 53 at lung, 28 at liver and 26 in other sites. PET/CT and morphological imaging modalities findings were available in 198 patients. The results were positively concordant in 137 patients, negatively concordant in 23 patients and discordant in 38 patients (20 negative at ceCT/MRI vs positive at PET/CT and 18 positive at ceCT/MRI and negative at PET/CT) (K Cohen= 0.426; p<0.001). Sensitivities, specificities and accuracies of FDG PET/CT and morphological imaging for the detection of recurrent bladder and UTUC cancer were 94% (90%-97%) vs. 86% (81%-92%), 79% (67%-92%) vs. 59% (44%-74%) and 91% (87%-95%) vs. 81% (75%-86%), respectively.

Conclusions

FDG PET/CT has a high diagnostic accuracy for the identification of recurrent UC, particularly in patients with bladder cancer. Moreover, its performance seems higher than conventional imaging for both bladder and UTUC cancer.

Funding

None