POSTN and chronic rhinosinusitis with nasal polyps: Additionally, Takahiro Ninomiya et al. [39] found serum POSTN could be used for examining postoperative CRSwNP recurrence as a biomarker with the optimal cut-off point of 115.5 ng/ml according to the closet point top-left in ROC curve, which means serum POSTN could be a another candidate biomarker to predict postoperative recurrence.