Preoperative Dural Contact Correlates With the Risk of Nodular Leptomeningeal Failure Following Adjuvant Stereotactic Radiosurgery

Abstract

Surgical resection followed by adjuvant stereotactic radiosurgery (SRS) has become a widely accepted treatment modality for brain metastases (BM). Compared to Whole Brain Radiation (WBRT), this approach achieves equivalent overall survival (OS) while reducing cognitive toxicities and preserving quality of life. However, this method of treatment is associated with a unique pattern of treatment failure, ¨nodular leptomeningeal disease" (nLMD), that is distinct in terms of behavior, prognosis and management compared to classic leptomeningeal disease (cLMD). We aimed to identify factors associated with the incidence of nLMD in surgical cavities treated with SRS.After identifying all patients treated with surgery and SRS of BM from a prospective registry, magnetic resonance imaging (MRI) before and after surgery were used to characterize tumors on the basis of dural contact, size and location. We also determined whether treatment volumes (TV) included the surgical tract or the pre-surgical areas of tumor contact with sinus or dura and, if so, whether that was expanded by a 1-5mm or 6-10mm margin. Failures were classified as nLMD, cLMD, or local failure (LF). Survival rates were calculated using the Kaplan Meier method. Outcomes for nLMD, cLMD, and LF were calculated using the cumulative incidence method. The difference in groups was tested using the Fine-Gray competing risk model.130 patients with 132 cavities were identified. Median patient age was 61.5 (23-90), median number of BM was 1 (1-10), median target volume was 15.1cc (4-54). Twenty-one percent of tumors were infra tentorial. Ninety-seven tumors contacted the dura pre-operatively. OS at 12 and 24 months was 68% and 39%, respectively. Cumulative incidence of nLMD at 12 and 24 months was 17% and 22%, respectively and for cLMD it was 3% and 6%, respectively. The incidence of LF at 12 and 24 months was 10% and 17%, respectively. OS following nLMD vs cLMD at 6 and 12 months were 49% and 29%, and 29% and 0%, respectively. Of the factors examined, only pre-surgical dural contact correlated with time to nLMD failure (HR 0.2 (0.05-0.81) (P = 0.024). No factors examined correlated with time to cLMD failure. Among 9 patients for whom a 6-10 mm dural margin was added to the region of pre-surgical dural contact, there were no nLMD.Preoperative dural contact correlated with time to nLMD but not cLMD. Patients with nLMD lived longer than those with cLMD. Including the surgical tract, the radiation target did not influence time to nLMD or cLMD.E. Gutierrez: None. C.J. Villafuerte: None. B. Millar: None. N.J. Laperriere: None. T.D. Conrad: None. A. Kalyvas: None. G. Zadeh: None. M. Bernstein: None. J. Weiss: None. P. Kongkham: None. D.B. Shultz: None.