Therapeutic efficacy of plasmonic photothermal nanoparticles in hamster buccal pouch carcinoma Marwa Mounir Afifi, a,i Sahar M. El Sheikh, b Maha M. Abdelsalam, c,j Heba Ramadan, d Taissir A. Omar, e Maha El Tantawi, f Khaled M. Abdel-Razek, g and Mostafa Mohamed h Faculty of Dentistry; and Medical Research Institute, Alexandria University, Alexandria, Egypt Objectives. The objective of this study was to assess the short-term effect of plasmonic photothermal therapy (PPTT) on induced hamster buccal pouch (HBP) carcinoma. Study Design. Seventy-six Syrian golden male hamsters were used. The induced HBP carcinomas were directly injected with w30 nm gold nanospheres followed by 15 min laser exposure (PPTT). Results. PPTT caused rapid growth cessation and dramatic decrease in tumor sizes after 4 weeks of treatment (P < .05) compared to controls. Microscopic and immunohistochemical examination of the tumor biopsies revealed significant differences in the cellular apoptotic index (AI) value and proliferating cell nuclear antigen (PCNA) immunoexpression in PPTT-treated tumor tissue sections compared to controls (P < .05). Survival probability of the treated animals was increased compared to controls (P < .05). Conclusion. PPTT proved to be a successful method for treating superficially located HBP carcinomas. (Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:743-751) Oral squamous cell carcinoma (OSCC) is the 8th most common cancer in the world. 1 It is an aggressive malignancy that invades local tissue, has the ability to metastasize and a poor 5-year survival rate. 2 Con- ventional treatment strategies (surgery and chemo- radiotherapy) have experienced significant advances over the past few decades, yet they remain far from op- timal. 3 Currently, cancer research focuses on improving cancer diagnosis and treatment methods via new tech- niques, among which are using nano-scaled particles. Nanotechnology involves the design, characterization, production and application of nano-scaled structures, devices, and systems. 4 In medicine, it is a promising tool for molecular diagnostic probes and novel therapeutic devices, such as photothermal and magneto- thermal probes, drug- and gene-delivery vectors, and radiation enhancers. 5 Noble metal nanoparticles provide remarkable opportunities in cancer imaging and therapy due to their unique optical properties and low cellular toxicity. 6 Photothermal therapy (PTT), which utilizes hyper- thermia, has been widely approved as a minimally invasive cancer treatment method. 7,8 However, it is underutilized in routine clinical practice due to the lack of tumor specificity and difficulties in heating deep tumors to therapeutic temperatures. 9 Progress in nano- medical research has surpassed these limitations by tar- geting tumor cells using metal nanoparticles. When an electromagnetic energy source is applied, metal nano- particles strongly absorb the electromagnetic energy and convert it into heat due to electron excitations and relax- ations, 10 hence the name plasmonic photothermal therapy (PPTT). 11 Hirsch et al., in 2003 12 first reported using gold- silica coreeshell nanoparticles for PPTT. Subsequently, El-Sayed and coworkers 6 have presented gold nanorods as promising PPTT agents capable of selective destruction of malignant cancer cells, while leaving healthy cells unaf- fected. A review by Jain reported that gold nanoparticles (AuNPs) are the most commonly used nanoparticles in Financial support information: Alexandria University, Egypt. a Assistant lecturer, Department of Oral Pathology, Faculty of Dentistry, Alexandria University, Azarita. b Professor, Department of Oral Pathology, Faculty of Dentistry, Alexandria University, Azarita. c Professor, Department of Oral Pathology, Faculty of Dentistry, Alexandria University, Azarita. d Lecturer, Department of Medical Biophysics, Medical Research Institute, Alexandria University, Hadara. e Professor, Department of Oral Pathology, Faculty of Dentistry, Alexandria University, Azarita. f Assistant Professor, Department of Pediatric Dentistry and Dental Public Health, Faculty of Dentistry, Alexandria University, Azarita. g Head, Medical Research Institute, Alexandria University, Hadara. h Professor, Department of Medical Biophysics, Medical Research Institute, Alexandria University, Hadara. i Current affiliation: Department of Chemistry and Biochemistry, Georgiatech Institute of Technology, Atlanta, GA, USA. j Present address: University of Dammam, College of Dentistry, P.O. Box 1982, Dammam 31441, Saudi Arabia. Received for publication Aug 1, 2012; returned for revision Nov 19, 2012; accepted for publication Nov 27, 2012. Ó 2013 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2012.11.020 Statement of Clinical Relevance Plasmonic photothermal therapy significantly de- creased hamster buccal pouch tumor volumes and increased animals survival rate. As buccal pouch carcinomas strongly resemble human oral squamous cell carcinoma, there is growing optimism to adapt this line of treatment to humans in the future. 743 Vol. 115 No. 6 June 2013