Additional file 1 of Preoperative profiles of plasma amino acids and derivatives distinguish periampullary cancer and benign disease

Additional file 1. Differences in metabolite profiles ascribable to pre-processing methods. Boxplots illustrating differences in metabolite profiles between samples pre-processed shortly after collection and samples stored at 4 °C overnight before pre-processing from A: benign (Immediate N = 11, Overnight N = 32, NA = 2) and B: malignant samples (Immediate N = 22, Overnight N = 38, NA = 6), respectively. On the x-axis, the metabolite concentration (log2-transformed and mean centered). Samples from patients that received neoadjuvant chemotherapy are excluded (N = 6). Wilcoxon’s Rank Sum Test was used to calculate the p-values. The p-values were adjusted by the Benjamini-Hochberg method. Significant difference in metabolite levels based on handling is marked with stars; *: FDR-value <= 0.05, **: FDR-value <= 0.01, ***: FDR-value <= 0.001, ****: FDR-value <= 0.0001.