Objective  To explore the expression of insulin-like growth factor 2 (IGF2) in urinary exosomes of patients with bladder urothelial carcinoma, and to evaluate its clinical value in the diagnosis of bladder urothelial carcinoma.

  Methods  Patients with bladder urothelial carcinoma or non-urothelial carcinoma diagnosed and treated by Peking Union Medical College Hospital from September to December 2020 were prospectively selected as the research subjects. Fluorescence quantitative reverse transcription PCR was used to detect the expression levels of IGF2 in the urine exosomes of the two groups. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of IGF2 in urinary exosomes for diagnosing bladder urothelial carcinoma were calculated, using pathological results as the gold standard.

  Results  A total of 35 patients with bladder urothelial carcinoma and 60 non-urothelial carcinoma patients who met the inclusion and exclusion criteria were selected. The positive expression rate of IGF2 in urinary exosomes in patients with bladder urothelial carcinoma was significantly higher than that in patients with non-urothelial carcinoma (71.4% vs. 10.0%, P=0.000). The sensitivity of IGF2 in urinary exosomes for diagnosing bladder urothelial carcinoma was 71.43% (95% CI: 53.48%-84.76%), the specificity was 90.00% (95% CI: 78.83%-95.87%), the positive likelihood ratio was 7.14 (95% CI: 3.25-15.70), the negative likelihood ratio was 0.32 (95% CI: 0.19-0.54).

  Conclusions  IGF2 is highly expressed in urinary exosomes of patients with bladder urothelial carcinoma, which has high diagnostic specificity for bladder urothelial carcinoma, but a slightly lower sensitivity. IGF2 is expected to be used as a primary screening index for bladder urothelial carcinoma.