Single studies also reported no association of serum ghrelin levels with head and neck cancers (Ozsoy et al. 2015) and thyroid cancer (Morpurgo et al. 2005), and inverse correlations of ghrelin with both presence of acute lymphoblastic leukemia and tumor burden (Moschovi et al. 2008) (Table 1). This evidence concerns the gene GHRL and acute lymphoblastic leukemia.