Thus, future studies must analyze the expression of the acid sphingomyelinase in the entire tumor including all types of host cells, blood leukocytes, local lymph nodes, the bone marrow, and, if possible, also the spleen, as well as of the secretory acid sphingomyelinase in the blood plasma, to define which cell type(s) has a high expression of the acid sphingomyelinase and may control the present phenotype. The gene discussed is SMPD1; the disease is neoplasm.