S100A9 and pachyonychia congenita: Furthermore, the percentage of weight loss within 6 months before cancer diagnosis in PC patients positively correlated with serum levels of S100A8 (r = 0.33, P < 0.001), S100A9 (r = 0.30, P < 0.001), and S100A8/A9 (r = 0.24, P = 0.004; Fig. 5a-c).