Impact of Secondary Aneurysmal Bone Cysts on Survival of Patients with Enneking Stage IIB Extremity Osteosarcoma: A Propensity Score Matching Analysis

Background The clinicopathology of aneurysmal bone cysts (ABCs) secondary to osteosarcoma has not yet been reported. We conduct a retrospective review of ABCs secondary to osteosarcoma to characterize clinicopathology and influence on the survival of patients with Enneking stage IIB extremity osteosarcoma. Patients and Methods A total of 300 patients with Enneking stage IIB extremity osteosarcoma were eligible for analysis. These cases were divided, according to the pathology of biopsy and magnetic resonance imaging (MRI), into ABCs group and no ABCs group. Patients (ABCs versus no ABCs) were compared using a 1:2 propensity score analysis to best match between groups. Clinicopathology and survival data were analyzed. Results The total occurrence rate of secondary ABCs was 10.3%. A higher prevalence of pathological fractures was observed in the ABCs group (22.6%) compared with the no ABCs group (8.6%) ( p = 0.032). Patients with ABCs were more likely to undergo amputation compared with patients without ABCs ( p = 0.007). Those with secondary ABCs had poorer response to chemotherapy before and after propensity score matching ( p = 0.006 and p = 0.048, respectively). Kaplan–Meier survival analysis showed that EFS and OS distributions were not significantly different between the two patient groups. ABCs were not significantly different in terms of EFS or OS in the multivariate analysis model ( p > 0.05). Conclusions The presence of secondary ABCs was associated with increased occurrence rate of pathological fracture and high percentage of amputation. Moreover, patients with secondary ABCs had poorer response to chemotherapy. However, the presence of secondary ABCs did not influence survival of patients with Enneking stage IIB extremity osteosarcoma.