The Combination of Cisplatinum and Doxorubicin Regressed Primary Osteosarcoma of the Breast in a PDOX Mouse Model

Background/aim Primary osteosarcoma of the breast is an exceedingly-rare malignant tumor that shares histological characteristics with osteosarcoma of the bone. Since effective therapies have not yet been established, standard therapy for osteosarcoma of the bone was examined in the present study for efficacy against primary osteosarcoma of the breast in a patient-derived orthotopic xenograft (PDOX) nude-mouse model. Materials and methods The PDOX mouse models were established by surgical implantation of the primary osteosarcoma of the breast specimen into the mammary gland of nude mice. Mice with tumors were randomized into four groups, each n=4: control group; cisplatinum (CDDP)-treatment group; doxorubicin (DOX)-treatment group; and CDDP/DOX-combination-treatment group. Mice were treated for twenty-one days, three weeks after implantation. Tumor size and body weight were measured during three weeks of treatment. Results Significant tumor growth inhibition was observed, compared to the control, in the CDDP-treatment group, the DOX-treatment group, and the combination-treatment-group. Only the combination treatment regressed the tumor. Conclusion CDDP and DOX which are standard first-line therapies for osteosarcoma, may be clinically effective against primary osteosarcoma of the breast, and in particular, their combination.