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Proceedings Paper

In vitro and in vivo studies of 2-photon photodynamic therapy for the treatment of conjunctival melanoma (Conference Presentation)
Author(s): Layla Pires; Shireen Khattak; Sebastião Pratavieira; Renan A. Romano; Vanderlei S. Bagnato; Yeni Yucel; Cristina Kurachi; Brian C. Wilson

Paper Abstract

Ocular melanoma is the second most common melanoma type after the cutaneous variety and represents about 3.7% of all melanomas. Of these, 82.5% are uveal, 6.6% are conjunctival and 10.9% occur at other sites. It is a potentially lethal disease, especially when it results in metastatic spread. Conventional treatments include radiation (brachytherapy, teletherapy), transpupillary thermotherapy, surgical resection (partial or full), enucleation, chemotherapy, and immunotherapy, but recurrences are frequent, with high morbidity depending on the initial tumor size. Two-photon photodynamic therapy (2-PE PDT) involves the use of ultrashort (fs) long-wavelength (near-infrared, NIR) laser pulses to excite the photosensitizer rather than low-intensity continuous light. The advantage is that melanin has a low NIR absorption, improving the light penetration into the tumor. Our in vitro studies show that 2-PE PDT is more efficient in melanotic than in amelanotic melanoma cells, while the control 1-PE PDT gives similar responses in both cell lines. In vivo, using conjunctival melanomas grown in 10 mice, histology shows apoptosis only at the treatment site, with no damage to the surrounding normal tissue. Also, in a single session, the technique could eliminate the entire tumor mass. These initial results suggest that 2-PE PDT has a high potential for the treatment of pigmented ocular melanomas and may represent a new alternative to conventional therapies.

Paper Details

Date Published: 14 March 2018
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Proc. SPIE 10476, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII, 104760O (14 March 2018); doi: 10.1117/12.2288544
Show Author Affiliations
Layla Pires, Instituto de Física de São Carlos (Brazil)
Shireen Khattak, Keenan Research Ctr. for Biomedical Science, St. Michael's (Canada)
Univ. of Toronto (Canada)
Sebastião Pratavieira, Instituto de Física de São Carlos (Brazil)
Renan A. Romano, Instituto de Física de São Carlos (Brazil)
Vanderlei S. Bagnato, Instituto de Física de São Carlos, Univ. de São Paulo (Brazil)
Yeni Yucel, Keenan Research Ctr. for Biomedical Science (Canada)
Cristina Kurachi, Instituto de Física de São Carlos, Univ. de São Paulo (Brazil)
Brian C. Wilson, Univ. of Toronto (Canada)
Princess Margaret Cancer Ctr., Univ. Health Network (Canada)


Published in SPIE Proceedings Vol. 10476:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII
David H. Kessel; Tayyaba Hasan, Editor(s)

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