IgD on IgD+ CD24+ B cell mediates the relationship between Bilirubin (Z,Z) to androsterone glucuronide ratio and the risk of SCLC, while IgD on IgD+ CD24+ B cell mediates the relationship between Bilirubin (Z,Z) to etiocholanolone glucuronide ratio and the risk of SCLC. Here, CD24 is linked to small cell lung carcinoma.