Catalytic nanomedicine: a new field in antitumor treatment using supported platinum nanoparticles. In vitro DNA degradation and in vivo tests with C6 animal model on Wistar rats.

Novel nanostructured TiO2 and SiO2 based biocatalysts, with 3-4 wt. % of Pt have been developed. The obtained materials exhibit a high surface area together with a broad pore size distribution. The method of synthesis allowed obtaining high dispersed platinum metal nanoparticles. In vitro DNA reactivity test of the biocatalysts were carried out by electrophoresis and formation of DNA adducts was observed. The most active biocatalyst was H2PtCl6/SiO2. These biocatalysts were also tested in an experimental model of C6 brain tumours in Wistar rats. Administration of the material was made by stereotactic brain surgery to place it directly in the malignant tissue. A significant decrease in tumour size and weight as well as morphologic changes in cancer cells were observed.

Tumor induction following intraoperative radiotherapy: late results of the National Cancer Institute canine trials.

Intraoperative radiotherapy has been employed in human cancer research for over a decade. Since 1979, trials to assess the acute and late toxicity of IORT have been carried out at the National Cancer Institute in an adult dog model in an attempt to establish dose tolerance guidelines for a variety of organs. Of the 170 animals entered on 12 studies with a minimum follow-up of 2 years, 148 dogs received IORT; 22 control animals received only surgery. Animals were sacrificed at designated intervals following IORT, usually at 1, 6, 12, 24, and 60 month intervals. 102 of 148 irradiated dogs were sacrificed less than 24 months; 46 dogs were followed greater than or equal to 24 months after IORT. To date, 34 of the 46 animals have been sacrificed; the 12 remaining animals are to be followed to 5 years. These 12 animals have minimum follow-up of 30 months. In the irradiated group followed for greater than or equal to 24 months, 10 tumors have arisen in 9 animals. One animal developed an incidental spontaneous breast carcinoma outside the IORT port, discovered only at scheduled post-mortem exam. The remaining nine tumors arose within IORT ports. Two tumors were benign neural tumors--a neuroma and a neurofibroma. One animal had a "collision" tumor comprised of grade I chondrosarcoma adjacent to grade III osteosarcoma arising in lumbar vertebrae. Two other grade III osteosarcomas, one grade III fibrosarcoma, and one grade III malignant fibrous histiocytoma arose in retroperitoneal/paravertebral sites. An embryonal rhabdomyosarcoma (sarcoma botryoides) arose within the irradiated urinary bladder of one animal. No sham irradiated controls nor IORT animals sacrificed less than 24 months have developed any spontaneous or radiation-induced tumors. The time range of diagnoses of tumors was 24-58 months (median 40 months). The IORT dose range associated with tumor development was 20-35 Gy (median 30 Gy). The carcinogenesis capability of single fraction, high dose radiation in animals is discussed, as are the implications of these data for continued research and clinical usage of IORT in the treatment of humans.