Bone Infarct-Associated Osteosarcoma: Epidemiologic and Survival Trends

Background: Bone tumors are not a frequent occurrence and bone infarct-associated sarcomas are even rarer. The prognosis of patients experiencing this disease is poor and treatment for them remains a challenge. Nevertheless, hardly any analyses in literature report on secondary osteosarcoma (SO) on bone infarct and most of the data available do not provide sufficient details. We evaluated whether this condition could be further characterized and if prognosis could be influenced by the chemotherapy (ChT) treatment. We sought to determine: (1) the main features of this rare disease; (2) the overall survival (OS) rate; (3) the OS rate associated to ChT treatment; and (4) the correspondence between our results and published data in terms of survival. Methods: We retrospectively reviewed patients admitted at the Rizzoli Orthopedic Institute of Bologna between 1992 and 2018 (1,465 total cases of osteosarcoma). We identified a list of 11 cases of SO on bone infarct (cohort 1). We conferred about the epidemiology, surgical and ChT treatment, and surveillance of infarct-associated osteosarcoma showing the correlation to data present in literature, corresponding to 14 case reports published within 1962-2018 (cohort 2). Results: (1) Cohort 1 was made of 11 patients: six females and five males, median age was 55 years. Nine (81%) were grade 4 and two (19%) were grade 3. Tumor predominantly arose on distal femur (64%). Most of patients had localized osteosarcoma at the diagnosis (81%); resection surgery was the elective treatment (73%) followed by amputation (18%). Of 11 patients, seven received also ChT (64%). (2) Five-year OS was 62% (95% confidence interval [CI]: 28-84). Median OS was 74 months (95% CI: 12-not reached). The cumulative incidence of cancer-related deaths (CICRD) was 37.7% (95% CI: 11.4-64.5) at 120 months. (3) In the group treated with only surgery, OS was 50% at 5 years. For patients treated with any form of ChT, OS was 71% at 5 years (p = 0.4773) and hazard ratio (HR) 0.56. The CICRD was 29% (at 2 years of follow-up. Instead, it was of 50% for patients treated only with surgery. (4) Median survival was 74 months and 12 months for cohort 1 and cohort 2, respectively (p = 0.0247). Data analysis showed a decreased HR for cohort 1 compared to cohort 2 (HR 0.315). Results confirmed also stratifying for age and ChT administration (HR 0.333). Conclusions: Based on this work, our opinion is that the treatment of SO patients with ChT combined to surgery improves patients' survival.