Influence of bony resection margins and surgicopathological factors on outcomes in limb-sparing surgery for extremity osteosarcoma

Background: Limb-sparing surgery for osteosarcoma requires taking wide bony resection margins while maximizing preservation of native bone and joint. However, the optimal bony margin and factors associated with recurrence and survival outcomes in these patients are not well established. Procedure: We conducted a retrospective review of outcomes in children and adolescents with newly diagnosed osteosarcoma from 1986 to 2012, where bony resection margins for limb-sparing surgeries were decreased serially from 5 to 1.5cm. The association between bony margins and other surgicopathological factors with survival and recurrence outcomes was determined. Results: In 181 limb-sparing surgeries in 173 patients, planned and actual bony resection margins were not significantly associated with local recurrence-free survival (LRFS), event-free survival (EFS), and overall survival (OS)-at median 5.8 years follow-up, decreasing planned bony resection margins from 5 to 1.5cm did not significantly decrease survival outcomes. Multivariable analysis showed that the presence of distant metastases at diagnosis was associated with decreased LRFS, EFS, and OS (P=0.002, 0.005, and <0.0001, respectively). Post-chemotherapy tumor necrosis ≤90% was associated with decreased EFS and OS (P=0.001 and 0.022, respectively). Earlier years of treatment and pathologic fractures were associated with decreased OS only (P=0.018 and 0.008, respectively); previous cancer history and male gender were associated with decreased EFS only (P=0.043 and 0.023, respectively). Conclusion: We did not observe significant increase in adverse survival outcomes with reduction of longitudinal bony resection margins to 1.5cm. Established prognostic factors, particularly histologic response to chemotherapy and metastases at diagnosis, remain relevant in limb-sparing patients.