# Saliva and blood miRNAs as complementary biomarkers for esophageal cancer detection

## TL;DR

This study explores the use of miRNAs in blood and saliva as non-invasive biomarkers for early detection of esophageal cancer.

## Contribution

The study evaluates the diagnostic performance of combined blood and saliva miRNAs compared to each individually for esophageal cancer detection.

## Key findings

- Combined blood- and saliva-derived miRNAs showed a pooled sensitivity of 0.79 and specificity of 0.77 for esophageal cancer diagnosis.
- Saliva-derived miRNAs had higher sensitivity (0.88) but lower specificity (0.60) compared to blood-derived miRNAs.
- The diagnostic accuracy of miRNA biomarkers was supported by high area under the SROC curve (AUC) values and diagnostic odds ratios.

## Abstract

Esophageal cancer is a highly aggressive malignancy with poor survival rates due to late-stage diagnosis. Early detection is crucial for improving prognosis, yet current diagnostic methods, such as endoscopy, are invasive and impractical for routine screening. Circulating microRNAs (miRNAs) have emerged as promising non-invasive biomarkers for cancer detection through liquid biopsy approaches. This meta-analysis aims to evaluate the diagnostic performance of circulating miRNAs in blood and saliva for esophageal cancer detection.

A systematic literature search was conducted in PubMed, Web of Science, and Scopus to identify relevant studies published between 2004 and 2024. Eligible studies included those that evaluated miRNA expression in plasma, serum, or saliva of esophageal cancer patients. The analysis assessed the diagnostic accuracy of circulating miRNAs in three distinct categories: combined blood- and saliva-derived miRNAs, blood-derived miRNAs, and saliva-derived miRNAs. Pooled sensitivity, specificity, summary receiver operating characteristic (SROC) curves, diagnostic likelihood ratios, and diagnostic odds ratios were evaluated to determine the reliability of these biomarkers.

A total of 27 articles encompassing 47 sub-studies with 2,396 patients were included in this meta-analysis. The pooled sensitivity of combined blood- and saliva-derived miRNAs for esophageal cancer diagnosis was 0.79 (95% CI: 0.76–0.82), with a specificity of 0.77 (95% CI: 0.72–0.80). Blood-derived miRNAs alone demonstrated a sensitivity of 0.77 and specificity of 0.79, while saliva-derived miRNAs alone exhibited higher sensitivity of 0.88 but lower specificity of 0.60. The area under the SROC curve (AUC) was 0.85 for both combined and blood-derived miRNAs, and 0.83 for saliva-derived miRNAs, demonstrating strong overall diagnostic accuracy. Diagnostic odds ratios further supported the clinical utility of miRNA biomarkers. Deeks’ funnel plot asymmetry test revealed no significant publication bias.

Circulating miRNAs show strong potential as liquid biopsy biomarkers for the non-invasive diagnosis of esophageal cancer. While saliva-derived miRNAs exhibit higher sensitivity, blood-derived miRNAs provide greater specificity. These findings indicate the need for further validation and standardization of miRNA-based assays to facilitate their integration into clinical practice for early detection of esophageal cancer.