CCKBR and small cell lung carcinoma: CCK2 receptors are expressed at high incidence in medullary thyroid carcinomas (MTC, > 90%), small cell lung cancers (> 50%), astrocytomas (> 60%), insulinomas, stromal ovarian cancers, gastrointestinal stromal tumors, and more than 20% of gastroenteropancreatic tumors (Reubi et al. 1997).