O-01 Case report: Temozolomide treatment of refractory prolactinoma

Abstract

Abstract Introduction Treatment of refractory prolactinoma is challenging. Temozolomide (TMZ), an oral chemotherapeutic agent, has been recommended as an effective drug for refractory pituitary adenomas or carcinomas. Clinical Case We report a 53-year-old male who presented with diplopia, left eye proptosis, conjunctival congestion, and headache. Magnetic resonance imaging (MRI) showed a macroadenoma 20×17 mm in diameter with compression of the optic chiasm and invasion of both cavernous sinuses. Hormonal evaluation revealed hyperprolactinemia of 2382 ug/L, 120x above the upper limit of normal (ULN), with central hypothyroidism and hypogonadism. Cabergoline was recommended as an initial treatment. Despite the maximum cabergoline dose of 1.5 g daily, tumor volume increased with visual disturbances and headaches. Prolactin (PRL) remained 60x above ULN so the patient underwent transsphenoidal surgery. Tumor histology was consistent with an atypical pituitary adenoma, positively stained for prolactin and sporadically for growth hormone, Ki-67 of 6.4%, no mitosis and negative p53. Postoperatively, the PRL level was still high (25x above ULN) with tumor remnants in both cavernous sinuses. Due to the tumor resistance to dopamine agonist treatment and uncomplete surgical resection, patient underwent stereotactic gamma knife radiosurgery (GK prescription dose 22 Gy, isodose 49%) simultaneously with TMZ treatment. After 2 cycles of TMZ (1. cycle TMZ 300mg/5days, 2. cycle TMZ 400 mg/5days), the PRL level decreased significantly (126 ug/L). The plan is to apply a total of 6 cycles of temozolomide. Conclusion Clinical evidence for the efficacy of TMZ in refractory prolactinoma remains limited, but early use of this agent may be helpful in some cases.