Effects of pre-radiation exposure to LLLT of normal and malignant cells

Purpose Low-level laser therapy (LLLT) efficacy for the prevention of cancer treatment-induced oral mucositis (OM) has been amply described. However, potential protection of malignant cells remains a legitimate concern for clinicians. We tested LLLT-induced protection from ionizing radiation killing...

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Bibliographic Details
Published in:Supportive care in cancer 2016-06, Vol.24 (6), p.2497-2501
Main Authors: Barasch, Andrei, Raber-Durlacher, Judith, Epstein, Joel B., Carroll, James
Format: Article
Language:English
Subjects:
Analysis
Cancer
Cell Line
Cell Survival - radiation effects
Disease prevention
Dose-Response Relationship, Radiation
HL-60 Cells
Humans
Inflammation
Ionizing radiation
Laser surgery
Laser Therapy
Lasers
Leukemia
Leukemia - radiotherapy
Low-Level Light Therapy - methods
Lymphocytes - radiation effects
Medical lasers
Medicine
Medicine & Public Health
Nursing
Nursing Research
Oncology
Oral diseases
Original Article
Pain Medicine
Radiation exposure
Radiation therapy
Rehabilitation Medicine
Stomatitis - pathology
Stomatitis - prevention & control
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Summary:Purpose Low-level laser therapy (LLLT) efficacy for the prevention of cancer treatment-induced oral mucositis (OM) has been amply described. However, potential protection of malignant cells remains a legitimate concern for clinicians. We tested LLLT-induced protection from ionizing radiation killing in both malignant and normal cells. Methods We treated six groups each of normal human lymphoblasts (TK6) and human leukemia cells (HL60) with He-Ne LLLT (632.8 nm, 35 mW, CW, 1 cm 2 , 35 mW/cm 2 for 3–343 s, 0.1–12 J/cm 2 ) prior to exposure to ionizing radiation (IR). Cells were then incubated and counted daily to determine their survival. Optimization of IR dose and incubation time was established prior to testing the effect of LLLT. Results Growth curves for both cell lines showed significant declines after exposure to 50–200 cGy IR when compared to controls. Pre-radiation exposure to LLLT (4.0 J/cm 2 ) followed by 1-h incubation blocked this decline in TK6 but not in HL60 cells. The latter cells were sensitized to the killing effects of IR in a dose-dependent manner. Conclusion This study shows that pre-IR LLLT treatment results in a differential response of normal vs. malignant cells, suggesting that LLLT does not confer protection and may even sensitize cancer cells to IR killing.
ISSN:0941-4355
1433-7339
DOI:10.1007/s00520-015-3051-8