Endocrine malignancies are rare tumors that are derived from endocrine cells located throughout the body. They encompass a heterogeneous group of malignancies, derived from different endocrine and neuroendocrine cells and have different clinically. The majority of endocrine neoplasms are benign, where the potential for invasion or metastasis is very low. Nevertheless, there is a group of endocrine neoplasms with malignant potential, and thus come under the management of medical oncology, often requiring systemic therapy. These include neuroendocrine tumors, anaplastic and medullary thyroid carcinomas, pheochromocytomas or paragangliomas, and adrenocortical carcinomas. While surgery continues to play a seminal role, the management of advanced endocrine neoplasia is more complex due to their rarity and heterogeneity. This book discusses the use of targeted therapy in the treatment of solid tumors and hematologic malignancies.