Clinical significance of urinary SPP1 as a potential new diagnostic marker for oesophageal squamous cell carcinoma

Urinary proteins could be useful as noninvasive biomarkers for the detection of oesophageal squamous cell carcinoma (ESCC). We assessed the levels of secreted phosphoprotein 1 (SPP1) in urine samples from patients with ESCC and evaluated its potential as a diagnostic biomarker. Urinary SPP1 levels were measured in 29 ESCC patients and 30 healthy controls using an enzyme‐linked immunosorbent assay. SPP1 expression was subsequently examined in tumour tissues and paired peritumoural normal tissue from the patients via immunohistochemistry. The diagnostic performance of SPP1 for ESCC was evaluated using receiver operating characteristic curve analysis. Urinary SPP1 levels were significantly higher in the ESCC group than in the control group. This parameter demonstrated discriminatory power between the groups, with an area under the curve of 0.7. Furthermore, immunohistochemical analysis confirmed that SPP1 expression was markedly upregulated in ESCC tissues compared with that in paired normal tissues. Moreover, subgroup analysis revealed that urinary SPP1 also effectively identified patients with stage III ESCC. Our study suggests that urinary SPP1 may serve as a novel biomarker for the detection of ESCC.