After 10 years, this second edition is extensively rewritten and updated and provides a source of information concerning all aspects of medullary thyroid carcinoma, including comprehensive actual references for interested scientists. Medullary thyroid carcinoma (MTC) is a rare unique tumor which differs from other thyroid tumors by originating from the neuroendocrine C-cell, secreting the specific tumor marker calcitonin. MTC is associated in about 25% of cases with multiple endocrine neoplasia type 2, an autosomal dominant familial disorder causing tumors within various endocrine glands. The molecular genetics of tumor development is clarified: hereditary as well as sporadic MTC are linked to mutations in the RET proto- oncogene coding for a tyrosine kinase. These RET mutations serve as a genetic marker for hereditary MTC and allow for prophylactic thyroidectomy in gene carriers. The RET-tyrosine kinase is also a new therapeutic target using selective tyrosine kinase inhibitors improving the outcome of advanced metastasized MTC. This book will be an ideal source of up-to-date information for a wide range of practitioners, including endocrinologists, oncologists, internal medicine specialists, geneticists, and nuclear medicine physicians.