Serum soluble signal regulatory protein alpha as a potential prognostic biomarker after surgery for esophageal cancer

Signal Regulatory Protein Alpha (SIRPα) and CD163 are associated with prognosis in esophageal cancer, but their prognostic value in blood is unknown. We retrospectively analyzed a randomized controlled trial of patients undergoing surgery for esophageal cancer. Soluble SIRPα (sSIRPα) and CD163 (sCD163) were measured using enzyme-linked immunosorbent assays in serum collected on the day of surgery and postoperative day 30. Patients were followed for one year. 68 patients were included. In patients undergoing upfront surgery (n = 15), high sSIRPα predicted increased 1-year mortality and sSIRPα <23.35 μg/L identified a low-risk subgroup (N = 7/15, 46.7%) with 100% 1-year survival. In contrast, among patients receiving neoadjuvant chemotherapy (CROSS or FLOT, n = 53), low sSIRPα predicted increased 1-year mortality and sSIRPα >26.15 μg/L identified a low-risk subgroup (N = 31/53, 58.5%) with 100% 1-year survival. There was no prognostic value in sCD163. In conclusion, neoadjuvant treatment may influence the prognostic value of sSIRPα in esophageal cancer.