title: Treatment of canine osseous tumors with photodynamic therapy: a pilot study.
abstract: Photodynamic therapy uses nonthermal coherent light delivered via fiber optic cable to locally activate a photosensitive chemotherapeutic agent that ablates tumor tissue. Owing to the limitations of light penetration, it is unknown whether photodynamic therapy can treat large osseous tumors. We determined whether photodynamic therapy can induce necrosis in large osseous tumors, and if so, to quantify the volume of treated tissue. In a pilot study we treated seven dogs with spontaneous osteosarcomas of the distal radius. Tumors were imaged with MRI before and 48 hours after treatment, and the volumes of hypointense regions were compared. The treated limbs were amputated immediately after imaging at 48 hours and sectioned corresponding to the MR axial images. We identified tumor necrosis histologically; the regions of necrosis corresponded anatomically to hypointense tissue on MRI. The mean volume of necrotic tissue seen on MRI after photodynamic therapy was 21,305 mm(3) compared with a pretreatment volume of 6108 mm(3). These pilot data suggest photodynamic therapy penetrates relatively large canine osseous tumors and may be a useful adjunct for treatment of bone tumors.
authors.affiliation: Department of Orthopedic Surgery, University of California San Francisco, 500 Parnassus Ave., RM-340 MU-West, San Francisco, CA 94143, USA. burchs@orthosurg.ucsf.edu
authors.forename: S
authors.initials: S
authors.lastname: Burch
authors.forename: C
authors.initials: C
authors.lastname: London
authors.forename: B
authors.initials: B
authors.lastname: Seguin
authors.forename: C
authors.initials: C
authors.lastname: Rodriguez
authors.forename: B C
authors.initials: BC
authors.lastname: Wilson
authors.forename: S K
authors.initials: SK
authors.lastname: Bisland
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*; D004285:Dogs; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D009336:Necrosis / Q000000981:diagnostic imaging / Q000473:pathology; D009367:Neoplasm Staging / Q000662:veterinary; D012516:Osteosarcoma / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*; D010778:Photochemotherapy / Q000379:methods / Q000662:veterinary*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D010865:Pilot Projects; D011877:Radionuclide Imaging
chemical_list: D017319:Photosensitizing Agents