Ovarian tissue stored for fertility preservation from 16 surviving patients diagnosed with sarcoma (nine with Ewing sarcomas, four with osteosarcomas, two with synovial sarcomas and one with chondrosarcoma) was evaluated for the presence of malignant cells by histology and by transplantation to immunodeficient mice for 20 weeks. A fraction of the tissue from patients with Ewing sarcoma was also evaluated for the presence of the molecular marker EWS-FLI1 by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The transplant itself and selected murine organs were analysed for the presence of malignant cells by histology.
All the mice accommodated the human tissue for 20 weeks of transplantation period with none of the mice developing any sign of cancer. In no instance were any cancer cells detected by histology or RT-qPCR.
Ovarian tissue from patients with sarcoma appears to be without metastatic malignant cells in numbers that allow detection. Although the actual pieces of ovarian tissue used for transplantation remain unchecked, the current data indicate that the procedure is safe at least in patients that survive the sarcoma disease.