Evaluation of expression of soluble form of SCF in CD117‐positive NK cells revealed no statistically significant differences between healthy donors and cancer patients due to the high level of variability in healthy volunteers, although the mean values were markedly higher in healthy donors: 2.81 ± 0.58 in patients (n = 13) versus 54 ± 32 (n = 9) in healthy donors (p = 0.08) (Fig. 3). This evidence concerns the gene KIT and cancer.