Additional Study Information: The purpose of this study is to assess the effectiveness of the therapy to be administered (how well it works) and the safety profile (if it has any unwanted effects on you that you can feel or on laboratory tests that are obtained) of lanreotide (a somatostatin analog (a hormone produced by the hypothalamus and some other tissues such as the pancreas and the gastrointestinal tract) that interferes with tumor growth) in subjects with advanced/metastatic pheochromocytoma or paraganglioma. You are being asked to participate in this study because you have metastatic pheochromocytoma or metastatic paraganglioma and you have never been treated with a somatostatin analogs. Approximately 40 individuals will be asked to participate in this study.