Combined treatment of invasive giant prolactinoma with surgical excision, low-dose gamma knife radiosurgery, and a dopamine agonist—Report of two cases

Tzu-Wen Loh^a, Tsung-Lang Chiu^{b, c}, Sheng-Wen Wu^b, Hsiang-Yi Hung^b, Kuan-Pin Chen^b, Chain-Fa Su^{b, c}

^a Department of Neurosurgery, Buddhist Dalin Tzu Chi General Hospital, Chiayi, Taiwan
^b Department of Neurosurgery, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
^c Department of Neurosurgery, Tzu Chi University, Hualien, Taiwan

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Abstract
Although most prolactinomas are benign, some are invasive or aggressive. The management of invasive giant prolactinomas (IGPs) has been an area of controversy. The present study reports the combined treatment of IGP with surgical excision, low-dose gamma knife radiosurgery (GKRS), and a dopamine agonist. An enhancing mass at the pituitary fossa with suprasellar extension and invasion of the cavernous sinus was identified in two patients. The blood prolactin level was more than 1000 ng/mL in both patients before treatment. Trans-sphenoidal removal of the tumors was done to reduce tumor compression on the optic apparatus. Low-dose GKRS was then used to treat the residual tumor with invasion to the caversinous sinus. The marginal dose was set at 12 and 14 Gy at the 50% and 42% isodose lines, respectively. A dopamine agonist, cabergoline, was used after GKRS. The tumors were markedly reduced and hard to be seen in magnetic resonance images. After a follow-up period of more than 3 years, the blood prolactin level returned to normal in one patient without the use of the dopamine agonist and was nearly normal in the other patient with continuing use of the dopamine agonist. Treatment combining surgical excision, GKRS, and a dopamine agonist may be a good treatment for IGPs. To make sure the remission of the disease, the longer follow-up is needed.

Keywords
Brain neoplasm; Gamma knife; Prolactinoma; Radiosurgery