Fig. 6.

PROCR serves as an important prognostic factor in NPC. a PROCR expression in sectioned NPC biopsy samples embedded in paraffin. According to the staining intensity, a total of 207 samples were divided into four groups denoted by 0 to 3. b Quantification of the PROCR expression level in metastatic or recurrent patients (n = 58) versus non - metastatic or non-recurrent patients (n = 149) based on IHC staining. The upper panel shows the proportion of PROCR⁺ tumor cells versus total tumor cells in each sample in different groups. The lower panel shows the average staining intensity of PROCR in different sample groups. ****P < 0.0001. c Kaplan–Meier curves for patients’ overall survival, disease-free survival, and distant metastasis-free survival according to PROCR expression (PROCR⁺ cells %). X-tile software was used to generate the optimal cut-off value to stratify patients at different risks. In total, 155 (74.9%) patients had a low PROCR, while 52 (25.1%) patients had a high PROCR