Next, by culturing the organoids in one medium for a period of time and then transferring them to another medium for further culturing, the expression of OLFM4 and CA2 in tumor tissue-derived organoid cells and normal tissue-derived organoid cells remained basically unchanged, indicating that the cultured medium that was initially used to derive the organoids plays a very critical role in the gene expression profiles of the organoids. The gene discussed is CA2; the disease is neoplasm.