Temozolomide cytoreductive treatment in a giant cabergoline-resistant prolactin-secreting pituitary neuroendocrine tumor

Dopamine agonists (DAs, especially cabergoline) are recommended as first-line treatment in patients with prolactin-secreting pituitary adenomas, to reduce hormone secretion and tumor size. Pituitary surgery, suggested in nonresponsive patients, cannot achieve a gross total resection or is not feasible in some cases. Temozolomide (TMZ) has been proposed in patients with aggressive pituitary neuroendocrine tumors (PitNETs) who do not respond to conventional treatments. We present a 47-year-old man with a giant (70×51×64 mm) prolactin-secreting PitNET. Cabergoline treatment (at first 1.5 mg/week, and then increased to 3.5 mg/week after 3 months) achieved prolactin suppression; however, magnetic resonance revealed a stable mass. After explanation of surgical complications, the patient rejected the procedure. Therefore, a primary neoadjuvant cytoreductive TMZ treatment was discussed during a meeting of the Pituitary Multidisciplinary Team, and added to cabergoline. After 13 cycles of TMZ (1 year of treatment), we observed dramatic reduction of the PitNET (from 18 cm of adenoma to 6 cm of necrotic tissue). MRI performed 4, 12, and 18 months after TMZ discontinuation revealed a stable residual PitNET, and 1.5 mg/week of cabergoline has been continued until today. Recently, the criteria for developing Pituitary Tumors Centers of Excellence have been proposed, indicating that a multidisciplinary team is the best care for patients. Surgery, rejected by the patient, could only achieve a partial resection; therefore, we decided to combine TMZ and cabergoline. An early initiation of TMZ could be considered in selected cases, especially when surgery could be only partially effective.