Although a detailed analysis according to the tumor extension was not possible in the SCLC group due to the reduced sample size, there was a notable difference between levels at limited and extended disease for HB-EGF (111.00 versus 236.00 pg/mL), EGF (78.37 versus 447.90 pg/mL) and CAL (97.32 versus 313.00 ng/mL). The gene discussed is HBEGF; the disease is small cell lung carcinoma.