 This study focusses on finding out if osteosarcoma can be detected in blood. The cells will be measured by a new laboratory technique called the polymerase chain reaction. This new technique can identify one tumor cell among one million normal cells. Using this technique Memorial Sloan-Kettering Cancer Center research doctors may be able to detect tumor cells that could not be identified any other way. This test will be in addition to cancer treatment and will not replace any other test used normally. As this technique is still unproved the results will not be given to patients or patients doctors and will not be used to change cancer treatment. 