CA9 and endometriosis: Significant differences were encountered between endometriosis and EC in case of five analytes, of which all were increased: ALDH1A (p = 0.019), CA9 (p = 0.031), CD44 (p = 0.010), hepsin (p = 0.007), midkine (p < 0.001) (Figs. 1, 2).