Gastrin-releasing peptide precursor is stable in blood, and high levels can be seen in lung tumors, neuroendocrine tumors, certain urinary system diseases, respiratory system diseases, and also in renal failure. Gastrin-releasing peptide precursor is a highly specific tumor marker for small-cell lung cancer, and serum concentration >150ng/L suggests that the possibility of small-cell lung cancer is as high as 93%. It is also seen in certain neuroendocrine cell tumors. It can also be elevated to varying degrees in certain benign diseases, such as urologic diseases and respiratory diseases, but the percentage of positivity is low. Renal failure can also result in elevated serum gastrin-releasing peptide precursors. In these cases, it is recommended that relevant tests and treatments be performed under the supervision of a physician.