title: Gold nanoparticle hyperthermia reduces radiotherapy dose.
abstract: Gold nanoparticles can absorb near infrared light, resulting in heating and ablation of tumors. Gold nanoparticles have also been used for enhancing the X-ray dose to tumors. The combination of hyperthermia and radiotherapy is synergistic, importantly allowing a reduction in X-ray dose with improved therapeutic results. Here we intratumorally infused small 15 nm gold nanoparticles engineered to be transformed from infrared-transparent to infrared-absorptive by the tumor, then heated by infrared followed by X-ray treatment. Synergy was studied using a very radioresistant subcutaneous squamous cell carcinoma (SCCVII) in mice. It was found that the dose required to control 50% of the tumors, normally 55 Gy, could be reduced to <15 Gy (a factor of >3.7). Gold nanoparticles therefore provide a method to combine hyperthermia and radiotherapy to drastically reduce the X-ray radiation needed, thus sparing normal tissue, reducing side effects, and making radiotherapy more effective.
  
  
  BACKGROUND
  Gold nanoparticles are known to enhance the efficacy of X-ray in tumor irradiation resulting in tumor heating and ablation. They also absorb near infrared light. This dual property was studied using a very radioresistant subcutaneous squamous cell carcinoma in mice, demonstrating that the dose required to control 50% of the tumors could be reduced by a factor of > 3.7, paving the way to potential future clinical applications.
authors.affiliation: Nanoprobes, Inc., Yaphank, NY, USA. Electronic address: hainfeld@nanoprobes.com.
authors.forename: James F
authors.initials: JF
authors.lastname: Hainfeld
authors.affiliation: Nanoprobes, Inc., USA.
authors.forename: Lynn
authors.initials: L
authors.lastname: Lin
authors.affiliation: Nanoprobes, Inc., USA.
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Slatkin
authors.affiliation: Department of Radiation Oncology, State University of New York at Stony Brook, USA.
authors.forename: F
authors.initials: F
authors.lastname: Avraham Dilmanian
authors.affiliation: Department of Civil and Environmental Engineering, University of Connecticut, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Vadas
authors.affiliation: Department of Cell Biology, University of Connecticut Health Center, USA.
authors.forename: Henry M
authors.initials: HM
authors.lastname: Smilowitz
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy* / Q000628:therapy*; D006046:Gold / Q000737:chemistry; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry / Q000627:therapeutic use*; D051379:Mice; D008819:Mice, Nude; D011878:Radiotherapy / Q000379:methods*
chemical_list: D006046:Gold
keywords: Cancer; Gold nanoparticles; Hyperthermia; Radiotherapy