Endocrinological evaluation of the efficacy of gamma knife radiosurgery for remnant tumor in cavernous sinus after trasnssphenoidal resection of growth hormone secreting pituitary macroadenoma

Abstract

OBJECTIVE: To determine long-term effect of gamma knife radiosurgery (GKS) for the treatment of remnant tumor in the cavernous sinus (CS) after transsphenoidal surgery (TSS) of growth hormone (GH)-secreting pituitary macroadenoma.METHODS: Seventeen patients who failed to achieve biochemical remission after TSS were followed for a mean period of 70.2 months (range 17-180) after GKS. All patients underwent regular hormonal examination including serum GH, IGF-1, oral glucose tolerance test, and combined pituitary function test(CPFT). Magnetic resonance imaging was performed 1-year after GKS and then subsequent 1.5-year interval. All patient had remnant tumor only in the CS and received hormone-suppressive medication, sandostatin LAR before or after GKS.RESULTS: There were 13 women and 4 men with a mean age of 41.8 years (range 27-62). 10 patients (58.8%) achieved hormonal remission with a mean time of 47 month (median 40, range 18-129) after GKS and mean marginal radiation dose was 27.9 Gy (range 14-35). Mean tumor volume decreased from 5.15ml (pre-GKS) to 3.55ml (last follow-up) (P <0.001). Actuarial rate of remission at 2,4, and 6 years were 12.5 %, 40%, and 64%, respectively. Intergroup comparison between remission and non-remission group those who had a minimum hormonal follow-up period of 48 months, showed both ‘serum level of GH’ and ‘degree of decreased GH percentile’ at 12 months after GKS showed significant difference (P=0.023), (P=0.014), respectively. A new pituitary hormone deficiency that has significant difference was found only in gonadal axis (P = 0.032) based on last follow-up CPFT. A radiation necrosis was detected in 4 patients.CONCLUSION: GKS in remnant tumor only in the CS after maximal resection of tumor in sellar and suprasellar area is effective especially for minimizing newly developed post-GKS hypopituitarism. However care should be done about radiation induced adjacent parenchymal necrosis after GKS in the CS especially.