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 patient's doctors and will not be used to change cancer treatment.

Inclusion Criteria:

• Patients with osteosarcoma are the study group
• Patients with malignant diagnoses other than osteosarcoma, neuroblastoma, Ewing's sarcoma or synovial sarcoma may participate as controls
• Histologically proven osteosarcoma or a history of histologically proven osteosarcoma are eligible for participation. The patient does not need to be newly diagnosed for enrollment on this protocol
• Patients with malignant diagnosis other than osteosarcoma, neuroblastoma, Ewing's sarcoma or synovial sarcoma are eligible to participate if they have a central venous catheter and routine blood work is being drawn

Exclusion Criteria:

• Patients less then three years of age
• Patients with Ewing's sarcoma, neuroblastoma and synovial sarcoma will be excluded from this protocol

Osteosarcoma patients seen in the Pediatrics Department or the Orthopedic Division of the Surgery Department at Memorial Sloan-Kettering Cancer Center