EGFR and non-small cell lung carcinoma: In some patients with non-small cell lung cancer (NSCLC), gefitinib treatment has resulted in impressive and long-lasting responses, but in clinical studies of other cancers expressing high levels of EGFR, such as prostate, breast, head and neck, CRC, mesothelioma, brain, kidney, gastric, and ovarian cancers, the drug has shown very limited activity, if any.