Second malignant neoplasms after treatment for osteosarcoma: a report of three cases.

We report second malignant neoplasms which developed between 7 and 19 years after treatment in 3 pediatric patients with osteosarcoma. Two patients had been treated with only surgery, and another patient had been treated with a combination of surgery with chemotherapy and radiation therapy for primary lesions. Pediatric patients with osteosarcoma, in particular, require careful long-term follow-up to monitor not only metastases but also development of second malignant neoplasms.