Low level laser therapy induces increased viability and proliferation in isolated cancer cells

Cell Prolif. 2018 Apr;51(2):e12417. doi: 10.1111/cpr.12417. Epub 2017 Nov 20.


Objectives: Low level laser therapy (LLLT), which stimulates natural biological processes in the application region, is frequently used in dental treatments. The aim of our study was to evaluate the effects of LLLT which could activate precancerous cells or increase existing cancerous tissue in case of clinically undetectable situations.

Materials and methods: Saos-2 osteoblast-like osteosarcoma cells and A549 human lung carcinoma cells were used. Twenty-four hours after preparation of cell culture plates, laser irradiation was performed 1, 2 and 3 times according to the test groups using Nd:YAG laser with the power output 0.5, 1, 2 and 3 W. Cell proliferation analysis was performed by MTT assay at the 24th hour following the last laser applications.

Results: Generally, it was observed that the proliferation rates increased as the number of applications increased, when compared to the controls, especially in those cases in which the irradiation was performed 2 or 3 times more.

Conclusion: The findings of this study have led to the conclusion that LLLT increases cancer cell proliferation, depending on the power output level of the laser and the number of applications. In addition to the proliferation and mitotic activity of the cancer tissue cells, we concluded that LLLT, which is frequently used in dental practice, could activate precancerous cells or increase existing cancerous tissue.

Keywords: Nd: YAG laser; low level laser therapy; lung carcinoma; osteosarcoma.

MeSH terms

  • A549 Cells
  • Bone Neoplasms* / metabolism
  • Bone Neoplasms* / pathology
  • Bone Neoplasms* / radiotherapy
  • Cell Proliferation / radiation effects*
  • Cell Survival / radiation effects
  • Humans
  • Low-Level Light Therapy*
  • Lung Neoplasms* / metabolism
  • Lung Neoplasms* / pathology
  • Lung Neoplasms* / radiotherapy
  • Osteosarcoma* / metabolism
  • Osteosarcoma* / pathology
  • Osteosarcoma* / radiotherapy