[Analysis of initial treatment only by linac-based stereotactic radiosurgery for a metastatic brain tumor from non-small cell lung cancer].

: A patient who receives stereotactic radiosurgery(SRS)alone for treating the brain metastatic lesion has a risk of tumor recurrence in the brain. Thus, some patients undergo prophylactic whole brain radiotherapy(WBRT)in addition to the SRS. However, the usefulness of adding WBRT is still debatable. In our hospitals, we initially treat metastatic brain tumors with SRS alone, and have experienced 2 long-surviving cases. Here, we report our treatment outcomes, including those for these 2 cases, and discuss the treatment plan for non-small cell lung cancer(NSCLC)with brain metastases. Forty-two brain metastatic cases were studied. Median survival(MS), tumor control rate(TCR), and recurrence ratio at distant site(RRDS)in the brain were analyzed. Age, Karnofsky performance status(KPS), and recursive partitioning analysis(RPA)class were analyzed as prognostic factors. We present 2 cases of a 42- and a 56-year-old man, surviving for more than 100 months. MS, TCR, and RRDS at 1 year in our hospitals were 20 months, 89.1%, and 25.6%, respectively. The prognostic factors were good KPS and RPA class and younger age. Our data showed a good MS among some reliable random controlled trials. Our strategy of SRS alone preserves the possibility to treat new lesions with WBRT. Prognosis was mainly defined by the systemic condition of the patient and activity of the primary lesion. Thorough treatment of the primary lesion with addition of SRS for initial treatment of metastatic lesions and scheduled MRI follow-up will provide for longer survival times.