Optimization of a metastasizing human gastric cancer model in nude mice.

Our purpose was to optimize the surgical orthotopic implantation (SOI) technique to create a reproducible gastric cancer model in nude mice with stable tumor growth and metastasizing course. We performed xenotransplantation of primary human tumor specimens from patients with gastric cancer (series 1) and orthotopic transplantation of tumor specimens originating from the gastric cancer cell line 23132/87 (series 2). All specimens were transplanted using microsurgical techniques. The two series were compared with regard to tumor growth rates and kinetics, development of metastases, and induction of minimal residual disease (MRD), as determined by histology and PCR techniques. In series 1 mice, the tumor growth rate was slow; in series 2 mice, it was both fast and reproducible. Unlike animals in series 1, animals in series 2 developed metastases and MRD. In conclusion, the optimized SOI technique presented here represents a reproducible and reliably metastasizing gastric cancer model.