Brain metastasis: Prognostic value of the number of involved extracranial organs

Background and purpose: This study was performed to evaluate the prognostic role for survival of the number and the type of involved extracranial organs in patients with brain metastasis. Material and methods: The data of 1146 patients who received whole-brain radiotherapy (WBRT) alone for brain metastasis have been retrospectively analyzed. In addition to the number of involved extra cranial organs, seven potential prognostic factors were investigated including WBRT regimen, age, gender, Karnofsky Performance Score (KPS), primary tumor type, number of brain metastases, and the interval from cancer diagnosis to WBRT. Additionally, subgroup analyses were performed for patients with involvement of one (lung vs. bone vs. liver vs. other metastasis) and two (lung + lymph nodes vs. lung + bone vs. lung + liver vs. liver + bone vs. other combinations) extracranial organs. Results: The 6-month survival rates for the involvement of 0, 1, 2, 3, and ≥ 4 extracranial organs were 51, 30, 16, 13, and 10 %, respectively (p < 0.001). On multivariate analysis, the number of involved extracranial organs maintained significance (risk ratio 1.26; 95 % confidence interval 1.18-1.34; p < 0.001). According to the multivariate analysis, age (p < 0.001), gender (p = 0.002), and KPS (p < 0.001) were also independent prognostic factors for survival. In the subgroup analyses of patients with involvement of one and two extracranial organs, survival was not significantly different based on the extracranial organ involved. Conclusion: The number of involved extracranial organs proved to be an independent prognostic factor in patients with brain metastasis, regardless of the organs involved. The number of involved extracranial organs should be considered in future trials designed for patients with brain metastasis.