1214P - Prognostic value of 68Ga-FAPI PET/CT in esophageal squamous cell carcinoma: A pilot study

Background

The prognostic value of ⁶⁸Ga-FAPI PET/CT has not been evaluated in any cancer type. We aimed to investigate the association between patients’ survival and ⁶⁸Ga-FAPI PET/CT-derived parameters in ESCC. We hypothesized that parameters derived from baseline ⁶⁸Ga-FAPI PET/CT might be used for evaluating the prognostic value of chemoradiotherapy response in patients with ESCC.

Methods

We conducted a retrospective analysis from a prospective parent study (NCT04416165). A total of 34 patients with locally advanced ESCC who underwent paired ⁶⁸Ga-FAPI and ¹⁸F-FDG PET/CT from December 2019 to March 2021 were included. Maximum standard uptake value (SUVmax), mean SUV (SUVmean), Gross tumor volume (GTV), total lesion glycolysis (TLG), and TL-FAPI of the primary tumor from corresponding PET/CT were developed to predict the clinical outcome regarding the definitive chemoradiotherapy.

Results

After a median follow-up duration of 21 months (range, 13–26 months), 18 patients were confirmed to have progressive disease. A total of 16 patients died during the follow-up period, and all these patients died of progressive disease. The PET parameters, including SUVmax-FDG, SUVmax-FAPI, GTV_FDG, GTV_FAPI, TLG, and TL-FAPI in patients with T4 stage were significantly higher than those in patients with T2/T3 stage (all P < 0.05). Additionally, the SUVmax and GTV of the primary tumor derived from ⁶⁸Ga-FAPI PET/CT were significantly higher than those derived from ¹⁸F-FDG PET/CT (median SUVmax, 14.9 vs. 11.1; P = 0.002; median GTV, 20.3 cm³ vs. 14.6 cm³; P < 0.001). In the univariate Cox regression model, T stage, N stage, GTV_FDG, GTV_FAPI, TLG, and TL-FAPI were associated with progression-free survival (PFS). Meanwhile, T stage, GTV_FDG, GTV_FAPI, TLG, and TL-FAPI were associated with overall survival (OS). In the multivariate analysis, GTV_FAPI was an independent prognostic factor for predicting both PFS (P = 0.033) and OS (P = 0.042).

Conclusions

This pilot study revealed the prognostic value of ⁶⁸Ga-FAPI PET/CT in ESCC patients treated with definitive chemoradiotherapy. ⁶⁸Ga-FAPI PET/CT may aid in personalized patient management by steering treatment modifications before therapy. Further prospective studies with larger patient number and longer observations are needed.

Clinical trial identification

NCT04416165.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.