ESTRO 2024 - Abstract Book

S782

Clinical - CNS

ESTRO 2024

6. Lamkin DM, Spitz DR, Shahzad MM, Zimmerman B, Lenihan DJ, DeGeest K, Lubaroff DM, Shinn EH, Sood AK, Lutgendorf SK (2009) Glucose as a prognostic factor in ovarian carcinoma. Cancer: Interdisciplinary International Journal of the American Cancer Society 115(5):1021-1027

744

Digital Poster

Radiation-induced lymphopenia and its impact on survival in patients treated with brain radiotherapy

Naoko Ishida, Yukinori Matsuo, Aritoshi Ri, Saori Tatsuno, Masahiro Inada, Tomohiro Matsuura, Hiroshi Doi, Kiyoshi Nakamatsu, Makoto Hosono

Kindai University Faculty of Medicine, Radiation Oncology, Osaka-sayama city, Japan

Purpose/Objective:

Several studies have shown that total lymphocyte count (TLC) is associated with survival in malignancies [1]. Lymphocytes are highly sensitive to radiation, and lymphopenia could be induced by radiotherapy (RT) for metastatic brain tumours, although this has not been well studied. The purpose of this study is to investigate temporal changes in TLC and the impact of radiation-induced lymphopenia on survival in patients receiving brain RT.

Material/Methods:

Patients who underwent whole brain radiotherapy (WBRT), stereotactic radiosurgery/radiotherapy (SRS/SRT), or prophylactic cranial irradiation (PCI) between January 2019 and December 2021 were retrospectively reviewed. RT courses without baseline TLC data which were obtained within 2 weeks before the start of RT or those without any follow-up TLC data within 8 weeks after the completion of RT were excluded. Follow-up TLC data were evaluated at three time points: 0 – 2 weeks, 2 – 4 weeks and 4 – 8 weeks after completion of RT. If multiple TLC data were available for each time point, the averaged value was used as a data. Persistent lymphopenia was defined as less than 800/μL at any of the time points. Overall survival (OS) was estimated as the time from the first course of brain RT during the study period using the Kaplan-Meier method.

Results:

One hundred and fifty-two courses of brain RT, including 94 courses of WBRT, 44 courses of SRS/SRT and 14 courses of PCI, in 142 patients were eligible to this study. Patient characteristics are shown in Table. The most common dose prescriptions were 30 Gy in 10 fractions, 37.5 Gy in 15 fractions and 40 Gy in 16 fractions for WBRT; 20-25 Gy in 1 fraction and 24-30 Gy in 3 fractions for SRS/SRT; and 25 Gy in 10 fractions for PCI.

Table. Patient characteristics Factor

Group

Overall

WBRT

SRS/SRT

PCI