Implications Of Identification Of Additional Cerebral Metastases During Stereotactic Radiosurgery

Veronica Chiang1, Toral Patel2, Jonathan Knisely3

1New Haven, CT United States 2Yale University School of Medicine, New Haven,USA 3Manhasset, United States

Keywords: brain metastasis, Imaging, gamma knife, radiosurgery, brain tumor

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     MRI scans performed at the time of Gamma Knife treatment at our institution are typically performed using a higher dose of gadolinium at a higher MRI scan resolution than the referral scan with which the patient presents.   Often times, additional lesions are identified on the treatment MRI.  
     The significance of this change in number of identified lesions was investigated.
     We performed a single institution retrospective review of 132 consecutive patients
     We performed a retrospective review on the patients, undergoing their first radiosurgical procedure for the treatment of intracranial metastases. The primary endpoint was the change in number of metastases detected between the initial diagnostic MRI and the subsequent treatment MRI. A multivariate analysis was employed to identify variables which significantly affected the change in number of metastases. Additionally, the Kaplan-Meier method was used to examine the effect of a change in the number of metastases on overall survival.
      The median number of lesions treated was 2 (range: 1-21). The median number of pre-operatively identified lesions was 1 (range: 1-10). The most common source of primary tumor was lung (47%), followed by breast (20%) and melanoma (11%). The median survival was 9.85 months; 114 patients (86%) had confirmed deaths. Additional lesions were identified in 41% of treatment MRIs, as compared to the initial diagnostic MRI. The results of a multivariate linear regression demonstrate that identification of additional cerebral metastasis is dependent on the number of initially identified lesions (p=0.001) and the presence of progressive systemic disease (p=0.002). This relationship was independent of other factors analyzed, including age, sex, time between scans, whole brain radiotherapy, and primary pathology. Kaplan-Meier analysis (Figure 1) demonstrated a significant decrease in survival for patients in whom additional metastases were identified (median 6.84 months, hazard ratio 1.48, p=0.038) when compared to patients in whom no additional metastases were identified (median 11.61 months). Of note, survival was independent of the number of initially identified lesions, however, there was a significant correlation between the number of additional metastases, documentation of progressive systemic disease and shortened median survival. 
     This is a retrospective study.
     This data highlights the dynamic nature of metastatic intracranial disease. 
     Identification of additional cerebral metastasis at the time of radiosurgical intervention yields important prognostic information about the state of systemic disease, which may be useful in directing patient care.


Project Roles:

V. Chiang (), T. Patel (), J. Knisely ()