No abstract

Background Hemolysis during blood drawing is a common cause of laboratory artifacts. Although circulating cell-free tumor DNA and fetal DNA are currently measured in routine practice, the effect of in vitro hemolysis on the measurement of cell-free DNA (cfDNA) has not been investigated. When in vitro hemolysis occurs, cellular DNA could be released from damaged white blood cells and reduce the fraction of circulating tumor DNA and fetal DNA. Methods Blood from healthy individuals was collected and passed through a narrow needle to cause in vitro hemolysis. Plasma was separated before and after mechanical damage, and concentrations of free hemoglobin and cfDNA of 2 reference genes were measured. Results cfDNA of 2 reference genes and free hemoglobin increased after mechanical damage. A clear correlation between cfDNA and free hemoglobin was observed. Conclusion cfDNA concentrations are higher in hemolyzed plasma. Therefore, the fraction of circulating tumor DNA and fetal DNA can be underestimated in plasma hemolyzed by inappropriate blood collection techniques.

We retrospectively enrolled 102 patients with upper tract urothelial carcinoma (UTUC) who underwent radical nephroureterectomy to examine the prognostic value of Ki-67 and programmed cell death ligand-1 (PD-L1). Then, we performed PD-L1 and Ki-67 immunohistochemical staining on whole tissue sections. The cut-off value of PD-L1 positivity was a combined positive score (CPS) ≥10 and the Ki-67 overexpression was 20%. Among the 102 patients, 16.7% and 48.0% showed positive PD-L1 expression and Ki-67 overexpression, respectively. A CPS ≥10 was significantly associated with a higher pathological T stage (p = 0.049). In addition, Ki-67 overexpression was significantly associated with a pathological T stage ≥ 2 (p = 0.027) and tumour necrosis (p = 0.016). In the multivariable analysis, a positive PD-L1 expression was significantly correlated with worse cancer-specific survival (HR = 3.66, 95% CI =1.37−9.77, p = 0.01). However, there was no predictive value using a combination of PD-L1 expression and Ki-67 overexpression as a prognostic predictor. Compared with Ki-67 overexpression, a positive PD-L1 expression with CPS ≥ 10 was a stronger independent prognostic factor for CSS in patients with UTUC.