Prognosis of interval distant metastases after neoadjuvant chemoradiotherapy for esophageal cancer

Background: In esophageal cancer patients, distant metastases develop between the start of neoadjuvant chemoradiotherapy and planned surgery, so-called interval metastases. The primary aim of this study was to assess management, overall survival (OS), and prognostic factors for OS in these patients. A secondary aim was to compare OS with synchronous metastatic patients. Methods: Esophageal cancer patients with interval distant metastases were identified from the Netherlands Cancer Registry (2010 to 2017). Management was categorized into metastasis-directed therapy (MDT), primary tumor resection, or best supportive care (BSC). The OS was calculated from the diagnosis of the primary tumor. Prognostic factors affecting OS were studied using Cox proportional hazard models. Propensity score-matching (1:3) generated matched cases with synchronous distant metastases. Results: In all, 208 patients with interval metastases were identified: in 87 patients (42%) MDT was initiated; in 10%, primary tumor resection only; in 7%, primary tumor resection plus MDT; and in 41%, BSC. Median OS was 10 months (interquartile range, 8.6 to 11.1). Compared with BSC, superior OS was independently associated with MDT (hazard ratio [HR] 0.36; 95% confidence interval [CI], 0.26 to 0.49), primary tumor resection (HR 0.55; 95% CI, 0.33 to 0.94), and primary tumor resection plus MDT (HR 0.20; 95% CI, 0.10 to 0.38). Worse OS was independently associated with signet ring cell carcinoma (HR 1.92; 95% CI, 1.12 to 3.28) and poor differentiation grade (HR 1.96; 95% CI, 1.35 to 2.83). The OS was comparable between matched patients with interval and synchronous distant metastases (10.2 versus 9.4 months, P =.760). Conclusions: In esophageal cancer patients treated with neoadjuvant chemoradiotherapy with interval distant metastases, the OS was poor and comparable to that of synchronous metastatic patients.