Validity of the Diagnosis-Specific Grading indexes for Radiosurgically-Treated Patients with Brain Metastases from Breast Cancer

Masaaki Yamamoto1, Takuya Kawabe2, Bierta E. Barfod3, Yoichi Urakawa3

1Ibaraki, Japan 2Hitachi-Naka, Japan 3Katsuta Hospital Mito GammaHouse

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

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Abstract

     Very recently, two diagnosis-specific grading indexes for patients with brain metastases (METs) from breast cancer were proposed; Diagnosis-Specific Graded Prognostic Assessment (DS-GPA, by Sperduto PW et al in Int J Radiat Oncol Biol Phys 2010;77:655-64) and Breast Cancer Recursive Partitioning Analisis (BC-RPA) Prognostic Index (by Nimiska A et al in Int J Radiat Oncol Biol Phys 2011 May 17Epub ahead of print). 
     We assessed whether the two indexes are valid for selecting patients with brain METs for gamma knife radiosurgery (GKS).
     A total of 269 consecutive female patients (mean age; 55 range; 26-86 years) in RPA Class I (n = 37, 14%), II (213, 79%) and III (17, 6%) formed the basis of this retrospective study.
     A total of 211 patients (78%) harbored multiple tumors (median tumor numbers; 5 range; 1-69). The mean clinical follow-up period was 14.9 (range; 0.2-138) months.
     Kaplan-Meier analysis demonstrated that the overall median survival time (MST) was 9.0 months: 17.1/8.4/2.7 months for RPA class I/II/III (p = 0.007 for I vs II and p=.0464 for II vs III). However, MSTs were 28.2/11.4/7.2/4.9 months for the DS-GPS groups of 3.5-4.0/3.0/1.5-2.5/0-1.0 (p=.1747 for 3.5-4.0 vs 3.0, p=.1561 for 3.0 vs1.5-2.5 and .467 for 1.5-2.5 vs 0-1.0). Also, MSTs were 9.0/9.7/0.8 months for the BC-RPA classes I/II/II (p = 0.9358 for I vs II and p<.0001 for II vs III). Both two diagnosis-specific indexes failed to imply the statistically significant differences of MST in patients with breast cancer, although RPA did not.
     
     Both grading systems, DS-GPS and BC-RPA, are not applicable to our set of patients for comparing their survival after GKRS. Although, there were large patient number discrepancies between the three classes, RPA system is still applicable.
     Grading systems should be validated.


Acknowledgements

Project Roles:

M. Yamamoto (), T. Kawabe (), B. Barfod (), Y. Urakawa ()