12 February 2018 Low-dose PDT on breast cancer spheroids
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Photodynamic therapy (PDT) has been investigated in clinical studies as a treatment method for breast cancer chest wall recurrences. Complete response percentage in these studies is not 100% in most patients, indicating the presence of a remaining tumor after PDT. Some in vitro studies show that tumor cells present distinct threshold dose, suggesting that the remaining tumor in vivo could require higher doses or different PDT strategies. There is still a lot of controversy of the multiple PDT sessions effect on bulky tumors. The purpose of this study is to investigate low-dose PDT parameters in 3D cultures of breast cancer cells grown by the magnetic levitation method. PDT was performed with Photodithazine® (PDZ) and LED irradiation at 660 nm. Two concentrations of PDZ were investigated and the 50 μg/mL concentration, which showed a superficial distribution, was used in the PDT. Partial damage was observed in the tumors and the viability test showed a small percentage of cell death. This outcome is favorable for the investigation of PDT effects in the remaining tumor. Multiple PDT sections could provide more noticeable alterations in cell morphology and metabolism.
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C. P. Campos, C. P. Campos, N. M. Inada, N. M. Inada, C. Kurachi, C. Kurachi, } "Low-dose PDT on breast cancer spheroids", Proc. SPIE 10476, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII, 104760S (12 February 2018); doi: 10.1117/12.2290915; https://doi.org/10.1117/12.2290915

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