Stereotactic radiosurgery as a primary treatmentmodality for pineal parenchymal tumors

Background: pineal parenchymal tumor (ppt) is extremely rare andhistologically heterogeneous, and the optimal treatment strategy iscontroversial. this study examined clinical outcomes of patients with ppttreated with cyberknife radiosurgery (ckrs) as a primary treatment modalityafter tumor biopsy. materials and methods: between 2009 and 2018, therewere six patients diagnosed with ppt who were treated with single orhypofractionated cyberknife radiosurgery (ckrs) after undergoing endoscopicthird ventriculostomy (etv) and tumor biopsy. two tumors werepineocytoma (pc) and four were pineal parenchymal tumor of intermediatedifferentiation (pptid). the marginal dose was 18 gy, and the median targetvolume was 3.05 (range 1.4-7.4) cc. the median follow-up period was 55(range 18 -141) months. results: five patients were alive, and all of theirtumors were locally controlled during follow-up periods. two tumorsdisappeared completely, two other tumors partially regressed, and anothertumor showed no interval change after ckrs. one patient with pptid showedlocal progression 14 months after ckrs and died 21 months after ckrs. therewere no acute or late complications related to ckrs. conclusion: this studysuggested that ckrs can be used as a primary treatment modality after etvand tumor biopsy for ppt with favorable clinical outcomes. however,alternative treatment modalities need to be considered for higher risk groupsof patients with pptid.