Osteosarcoma (1 ,2) and Ewing’ s sarcoma (3 ,4) are the two most common primary bone tumors in children. The 2-yr metastasis-free survival rate is 60-65% (5 -9) and 41% (10) in patients having osteosarcoma and Ewing’s sarcoma, respectively. These rates have not changed over the past 15 years despite numerous alterations in chemotherapy for these tumors (7 -9) . The most common site of metastatic spread of both of these tumors is the lung. Additionally, salvage chemotherapy regimens have shown only limited efficacy against them (11 -13 ). Therefore, new treatment strategies are needed to control or prevent lung metastasis and improve the long-term survival rate.
