Clinical Experience of Postoperative Gamma Knife Radiosurgery to the Surgical Bed at the 7 Day-Interval from Resection of Brain Metastsis

Abstract

Objective: To evaluate a properness about the median 7 day-interval of postoperative Gamma knife radiosurgery (GKRS), the authors compared the differences between outcomes of ours delivering postoperative GKRS with the median 7 day-interval and other researches delivering GKRS 2-6 weeks after surgical resection. Methods: From December 2008 to November 2011, 45 patients with brain metastases due to variable causes were treated with surgical bed GKRS after the median 7 day-interval from surgical resection. We retrospectively analyzed the results of surgical bed Gamma knife radiosurgery (GKRS) performed in our institute, and compared the local control rate with other researches through a literature review. Results: There were 33 men and 12 women whose mean age was 59 years (range 32-78 years). The most common primary lesion of brain metastases was in the lung in both genders. The operated tumors involved 38 supratentorial, and 7 infratentorial locations. At the start of treatment, 31 patients’ systemic disease was active and 14 patients’ was controlled. Nineteen patients had only one metastatic lesion, nine had two to three lesions, and 17 had more than four lesions. Forty-two cases of lesions were grossly total resected, and three were subtotal resected. The median interval from resection to GKRS was 7 days (range 3-19). Only 6 of 45 cases (13%) failed local control after surgical bed radiosurgery. The primary lesions of local failure were 3 esophageal cancer cases (50%), 1 lung cancer case (17%), 1 kidney cancer case (17%), and 1 colon cancer case (17%). All 6 cases were supratentorial lesions and grossly total resected. The median time to local control failure was 6 months (range 2-14 months). After GKRS, leptomeningeal carcinomatosis (LMC) were developed in one case (2%), positioned in supratentorial area, and the time to LMC was 2.4 months. Conclusion: We conclude that GKRS only after the surgical resection of brain metastases seems to be an effective treatment strategy and identified that postoperative GKRS with the median 7 day-interval, earlier than previous studies, gave an acceptable local control rate (87%) with a low LMC incidence as other surgical bed GKRS reports.