Gefitinib Treatment Was Unsuccessful for Central Diabetes Insipidus Due to Pituitary Metastasis of Lung Adenocarcinoma

We herein report a rare case of advanced lung adenocarcinoma with central diabetes insipidus due to pituitary metastasis. Although treatment with gefitinib was dramatically effective, the symptoms of diabetes insipidus did not improve. Radiotherapy for pituitary metastasis was effective to control diabetes insipidus; however, we could not cease the administration of 1-deamino-8-D-arginine vasopressin (DDAVP). It is important for physicians to positively consider radiotherapy for pituitary metastases even if favorable tumor control is achieved with chemotherapy when diabetes insipidus becomes clinically overt. Furthermore, continuous DDAVP administration may be needed to treat central diabetes insipidus.