CEACAM5 and neoplasm: Under CEA‐CAR‐T cell treatment or CEA‐CAR‐T cells in combination with rhIL‐12 treatment, there were significantly increased LDH levels in the supernatant of CEA‐positive tumor cell cultures and the LDH level under CEA‐CAR‐T cells in combination with rhIL‐12 treatment were significantly higher than CEA‐CAR‐T cells treatment.