Patient-derived orthotopic xenograft (PDOX) nude mouse model of soft-tissue sarcoma more closely mimics the patient behavior in contrast to the subcutaneous ectopic model

Aim: Soft-tissue sarcomas are a group of rare mesenchymal carcinomas that include approximately 50 histological types, and account for 1% of all adult cancer cases. The yearly incidence of soft-tissue sarcomas in the USA is approximately 11,280 cases, with an overall mortality of 3,900 deaths per year. Materials and Methods: In this study, we established a patient-derived orthotopic xenograft (PDOX) from a patient with a soft-tissue sarcoma of the retroperitoneum in nude mice and compared it to a subcutaneous patient-derived model of the same tumor for histology. Results: In the PDOX model, a bulky tumor grew in the left retroperitoneum in the same manner as the patient's tumor. Upon histological examination, the majority of the PDOX tissue section comprised sarcomatous highgrade spindle cells of varying sizes, similar to the original patient tumor. In contrast, the majority of the subcutaneously-implanted tumor comprised round to oval cells. Conclusion: These results indicate that the PDOX recapitulated the histology of the original tumor more than the subcutaneous model.