18F-FDG PET/CT metabolic parameter to predict pathological complete response and survival after neoadjuvant immunotherapy plus chemoradiotherapy in resectable esophageal squamous cell carcinoma

Abstract

Neoadjuvant immunotherapy plus chemoradiotherapy (nICRT) for esophageal squamous cell carcinoma (ESCC) received increasing attention because of high pathological complete response (pCR) rate. Accurately assessing residual disease after nICRT is beneficial for dynamic monitoring of patients. This exploratory, single-arm, phase II clinical study aimed to evaluate the diagnostic efficacy of 18F-FDG PET/CT for achieving pCR after nICRT for ESCC, and its prognostic value for survival. From January 12, 2021 to February 21, 2023, a total of 21 resectable ESCC patients receiving nICRT were enrolled and underwent baseline PET/CT scans (scan-1) and surgery. 19 patients underwent scans (scan-2) before surgery. The recorded PET/CT parameters included maximum, mean, and peak standardized uptake values (SUVmax, SUVmean, and SUVpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The diagnostic performance of PET/CT parameters was analyzed between the patients with pCR of the primary tumor (pCR-tu) and non-pCR-tu. The Cox regression and Kaplan-Meier method were performed for multivariable analysis and survival analyses, respectively. 13(61.9%) achieved pCR-tu after nICRT among the 21 participants. None of the single metabolic parameters of primary tumor were significant predictors of pCR-tu (all p > 0.05). SUVmax2 of lymph nodes (Ln) has diagnostic value for lymph nodes metastasis (p < 0.01), the area under the curve (AUC), sensitivity and specificity were 0.812, 77.8% and 76.9%, respectively. The 3-year overall survival (OS) and disease-free survival (DFS) rates were 76.2% and 66.7%, respectively. Univariate Cox regression indicated that OS and DFS were correlated with the postoperative ypN stage, ypTNM stage, pCR, pCR-tu, SUVmax2, and LnSUVmax2. Long rank analysis showed that patients with a cutoff value of ≥12.4 for SUVmax2 and of ≥7.9 for LnSUVmax2 had poorer OS and DFS. However, multivariate Cox regression showed that the parameters mentioned above were not independent prognostic factors for OS and DFS. None of the single metabolic parameters of the primary tumor were significant predictors of pCR-tu. LnSUVmax2 has diagnostic value for lymph nodes metastasis. The patients with SUVmax2 ≥ 12.4 and LnSUVmax2 ≥ 7.9 had poorer OS and DFS, but they are not independent prognostic factors, which needs to be confirmed by larger scale clinical studies. NCT05323890. Registered on April 5, 2022. Retrospectively registered.