POSTN and non-small cell lung carcinoma: To assess the prognostic value of the serum periostin levels, we used serum periostin cutoff value 30.87 ng/ml, which was calculated from ROC analysis, as a threshold to classified NSCLC patients into two groups, high serum periostin group (periostin ≥ 30.87 ng/ml) and low serum periostin group (periostin < 30.87 ng/ml).