Osteosarcoma Arising After Ewing Sarcoma orVice Versa: A Report of 20 Affected Patients from the Cooperative Osteosarcoma Study Group (COSS)

Abstract

Background/Aim: Ewing sarcoma can arise in patients after osteosarcoma or vice versa. Our aim was to learn more about which patients develop these secondary tumors, which treatments may be effective, and which patients might survive. Patients and Methods: The database of the Cooperative Osteosarcoma Study Group (1980Group ( -09/2022 was searched for all patients with an osteosarcoma (including undifferentiated pleomorphic sarcoma of the bone) who also suffered from Ewing sarcoma (incl. peripheral neuroectodermal tumor) at any time, previously or thereafter. The identified patients were then analyzed for patient, tumor, and treatment-related variables as well as their disease-and survival-status at the last follow-up.Results: A total of 20 eligible patients [17 Ewing sarcoma prior to osteosarcoma, 3 vice versa; 10 males, 10 females; median age at 1 st cancer 10.5 (2.4-20.6), at 2 nd cancer 20.5 (9.9-42.4) years] were identified. None of the patients developed a 3rd cancer and none had a known tumor-predisposition syndrome. Sixteen/17 secondary osteosarcomas and no secondary Ewing sarcoma developed in sites that had previously been irradiated. Nineteen/20 (95%) patients received primary multi-agent chemotherapy for their 1 st and 2 nd cancers. Actuarial overall and event-free survival probabilities at five years after the diagnosis of the secondary cancer were 69% and 42%, respectively. Conclusion: Secondary osteosarcoma arising after Ewing sarcoma is almost exclusively associated with radiation. This is not the case vice versa. Either way, long-term survival is a realistic possibility with appropriate multidisciplinary treatment; thus, therapeutic negligence is clearly inadequate.The combination of Ewing sarcoma with a later osteosarcoma is a feared complication in both pediatric and adult oncology. Osteosarcoma generally arises as the second tumor and is often assumed to be related to irradiation therapy for the first cancer (1-3). Secondary Ewing sarcoma, arising after an osteosarcoma, is also a possibility, but clearly represents the much less common order of events (4-10). This particular sequence of events is not assumed to be associated with tumor-predisposition syndromes or prior therapies.