Osteosarcoma and second malignant neoplasms: a case series.

BACKGROUND: The overall survival of patients with localised osteosarcoma has dramatically improved with the introduction of multidrug chemotherapeutic regimens into the treatment paradigm. However, despite optimal treatment, all-cause mortality remains higher among osteosarcoma survivors than in the general population. The development of second malignant neoplasms contributes to this higher mortality rate. CASE SERIES: We present three cases of patients definitively treated for osteosarcoma who subsequently developed a second malignant neoplasm. The first case describes a 17-year-old female with osteosarcoma of her right femur treated with surgical resection and perioperative chemotherapy. Ten years later, she was diagnosed with metastatic HER2-positive breast cancer. Genetic testing identified a germline TP53 mutation, confirming the presence of Li-Fraumeni syndrome. The second case details an 18-year-old male with osteosarcoma of his right humerus treated with definitive resection and perioperative chemotherapy. He was diagnosed with appendiceal adenocarcinoma after presenting with acute abdominal pain 17 years later. The third case reviewed is of a 36-year-old male with osteosarcoma of his right femur treated with definitive resection and adjuvant chemotherapy. A diagnosis of leiomyosarcoma was made 7 years later following surveillance imaging. DISCUSSION: The risk of second malignant neoplasms in osteosarcoma may relate to previous oncological treatment, an inherited cancer predisposition syndrome or a spontaneous new neoplasm. Although screening for a second malignancy is not routinely recommended for osteosarcoma survivors, a high degree of clinical suspicion should be maintained during surveillance.