A syndrome characterized by abnormal secretion of antidiuretic hormone in conjunction with neoplastic growth occurring anywhere in the body. The disease is inappropriate ADH syndrome (MONDO_0006802, a Monarch Disease Ontology id). Also known as: SIADH, ectopic ADH secretion, ectopic antidiuretic hormone secretion, inappropriate ADH secretion, inappropriate Arginine vasopressin secretion, inappropriate antidiuretic hormone secretion syndrome, syndrome of inappropriate antidiuretic hormone, syndrome of inappropriate antidiuretic hormone secretion.