Validation Of The Bsbm System?s Classification With An 8 Years Follow Up For Patients With Brain Metastases Treated By Leksell Gamma Knife Radiosurgery.

Keywords: brain metastasis, outcome, gamma knife, cancer, grading system

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     We proposed a few years ago a new system’s classification called Basic Score for Brain Metastases (BSBM) build on a retrospective study concerning patients with brain metastases (BM) treated by radiosurgery. The three significant prognostic factors were (i) a Karnosky Performance Status (KPS) equal or superior to 80 (no = 0; yes = 1 point), (ii) an absence of a systemic disease (no = 0; yes = 1 point ) and (iii) a primary disease controlled (no = 0; yes = 1 point). This classification varied from 0 to a 3 points. Since January 2003, we followed prospectively the new cohort of patients.
     This study analysed the survival of both (retrospective and prospective) populations.
     267 evaluable patients with more than 700 brain metastases were treated with a Leksell Gamma Knife model C.
      Median marginal dose was 20 Gy at a median 50 % isodose. There were 45% (119 pts) lung cancer, 22% (59 pts) breast cancer, 19% (49 pts) melanoma and 15% (40 pts) other primary tumors. The retrospective study concerned 110 patients treated from December 1999 and December 2002. The prospective study concerned 157 patients treated from January 2003 to December 2005.
     Median survival (MS) for the entire population is 11 months and 3, 6, 12 and 23 months for respectively BSBM 0, 1, 2 and 3 points subgroups. For the selective categories BSBM 0, 1, 2 and 3 points, the MS were respectively 3, 3.5, 11 and 20 months for the retrospective study versus 3.5, 7, 13 and 27 months for the prospective study. The multivariate analysis identifies as significant factors : the KPS, the SIR and the BSBM models. On the validation set, the discrimination power of the BSBM score assessed by the area under the ROC curve. The difference between the retrospective and the prospective subgroups is not statistically different.
     This is a retrospective study.
     The BSBM system’s classification is comparable in the retrospective and prospective studies. 
     This suggests the value of this new original classification.


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