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Published on: February 8, 2017
Radiation-Induced Lymphopenia and Its Impact on Survival in Patients with Brain Metastasis
Naoko Ishida1, Yukinori Matsuo1, Junki Fukuda1
1Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osakasayama 589-8511, Osaka, Japan.
Background:
Differences in radiation-induced lymphopenia and prognosis between methods of radiotherapy (RT) for brain metastases remain unclear.
Methods:
In this retrospective analysis of patients who underwent whole-brain radiotherapy (WBRT) or stereotactic radiosurgery/radiotherapy (SRS/SRT) for brain metastases, baseline total lymphocyte count (TLC) data were obtained within 2 weeks before RT initiation. Follow-up TLC data were evaluated at 0-2, 2-4, and 4-8 weeks after RT completion. Persistent lymphopenia was defined as <800/μL at any time point.
Results:
Overall, 138 RT courses in 128 patients were eligible (94 WBRT; 44 SRS/SRT). In the WBRT courses, the median baseline TLC was 1325/μL (IQR: 923-1799). Follow-up TLC decreased significantly to 946/μL (626-1316), 992/μL (675-1291), and 1075/μL (762-1435) (p < 0.001). SRS/SRT courses showed no significant TLC decrease. Multivariate analysis revealed female sex, prior RT, baseline TLC < 800/μL, and WBRT use were significantly associated with persistent lymphopenia. In the WBRT group, overall survival was significantly different between those with and without persistent lymphopenia (median, 2.6 and 6.1 months; p < 0.001). However, there was no significant difference in survival in the SRS/SRT group (p = 0.60).
Conclusion:
This study suggests SRS/SRT might be preferable for lymphocyte preservation in brain metastasis patients.
