Treatment of NETs from Rare Origin

Rare neuroendocrine tumours (NETs) closely resemble their lung and gastroenteropancreatic (GEP) counterparts, although it is still unknown whether they also share similar genetic alterations. Though surgery remains the first-line treatment for all NETs independently from their primary localization, a large number of them present metastases at diagnosis, thus requiring adjuvant therapies. The lack of large-scale studies on rare NETs leads to a lack of definitive biologic, epidemiologic and prognostic information, as well as standardized treatment guidelines. Indeed, it is unknown whether these tumours may benefit from treatment reserved for lung and GEP NETs or, on the contrary, should be treated similarly to epithelial cancers of the specific primary site. In this chapter, clinical presentation, diagnosis and treatment of oesophageal, thymic, renal/genitourinary and breast neuroendocrine tumours will be discussed.