A Case of Primary Osteosarcoma of the Mandible That Responded to Preoperative Chemotherapy: p16 as a Potential Prognostic Factor.

We report a case of mandibular osteosarcoma in a Japanese woman in her 70s who was p16-positive. Despite the rapid growth of the tumor, the patient responded well to chemotherapy and was then able to undergo surgery. Head and neck osteosarcoma (HNOS) is a very rare cancer, and although the importance of surgery has been pointed out, the effectiveness of chemotherapy is unclear. Resection margin negativity and response to chemotherapy have been reported as prognostic factors; another report assessed the effectiveness of the immunohistochemical expression of p16 protein as a predictor of response to chemotherapy.