Page 31 - SDIR5 Abstract book 21 12 2021.

RADIOBIOLOGY

Radiation-induced lymphocyte apoptosis as a possible biological predictor of radiotherapy
toxicity in prostate cancer patients

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Jelena Stanić , Vesna Stanković , Ivana Z. Matić , Tatjana Stanojković , Marija Đorđić Crnogorac , Ana
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Đurić , Marina Nikitović
1 Institute of Oncology and Radiology of Serbia, Department of Radiation Oncology, Belgrade, Serbia
2 Institute of Oncology and Radiology of Serbia, Department of Experimental Oncology
3 Faculty of Medicine, University of Belgrade, Belgrade, Serbia

Background: Localized prostate cancer (PC) can be treated with different therapeutic modalities that may
have a similar outcome but different toxicity profiles. Individual differences in radiation-induced toxicity,
even with the use of advanced radiotherapy (RT) techniques, such as intensity-modulated radiotherapy
(IMRT), are observed. Radiation-induced apoptosis of T lymphocytes could be used to identify
radiosensitive patients before RT. The aim of ongoing study is to investigate the possible correlations
between the levels of CD4+ and CD8+ T lymphocyte apoptosis and RT-induced acute and late adverse
reactions in patients with PC. Patients and methods: We have started to recruit patients with localized PC,
treated with IMRT, at the Institute of Oncology and Radiology of Serbia, since May 2021. Peripheral blood
samples are collected before RT. The samples are irradiated with 8 Gy (1Gy/min). Non-irradiated blood
samples are used as control samples. The percentages of CD4+ and CD8+ T lymphocytes in apoptosis are
determined by flow cytometry. Results: Irradiation of peripheral blood of patients induced diverse levels of
apoptosis of CD4+ and CD8+ T lymphocytes after 48h incubation. The possible associations between low,
medium and high apoptosis levels of T lymphocytes and acute and late normal tissue radiotoxicity are
examined. Conclusion: Predicting which patients will develop RT toxicity is important for determining the
optimal personalized therapeutic approach with the goal of long-term preservation of patient’s quality of
life. Assessment of individual and clinical parameters in addition to lymphocyte radiosensitivity may be
useful for identification of patients with higher risk of developing radiotoxicity.
Keywords: prostate cancer; radiotherapy; radiation toxicity, T-lymphocyte apoptosis

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