Surgical inaccuracy of pelvic tumour resections and implication on the oncologic outcomes. A centre-base study of 64 cases

Introduction: Safe surgical margins are difficult to achieve when performing surgical resections for bone and soft tissue tumours involving the pelvis. Even with the advancements in treatment modalities, the rates of cure for pelvic tumours are lower than those involving the long bones. We evaluated the accuracy of surgical margins achieved in pelvic tumour resections, its associated factors, as well as the oncologic outcomes. Materials and Methods: We reviewed 64 cases of pelvic tumours of various types, whom underwent internal (limb-salvage) or external hemipelvectomy in a single tumour referral centre between January 2001 and December 2010. Various clinicopathologic factors were analyzed in relation to achieving a negative microscopic margin in tumour resections. Survival time to local recurrence, distant metastasis, and disease-specific death of patients, as well as factors associated with the oncologic outcomes were analyzed. Results: Mean age at time of surgery was 39.84 years (range 8 to 79 years). Majority of cases were primary tumours (76.56%). The most common were chondrosarcoma (n=14) and osteosarcoma (n=13). Twenty-three patients underwent external hemipelvectomy and 41 patients subjected for internal hemipelvectomy of various types of resections. Majority (71.88%) of cases were treated with curative intention. Fourteen of 37 cases (37.84%) attempted for wide resection came back as having positive microscopic margins. Incidence of positive microscopic margin was higher in cases with wide contaminated margins (56.25%). Factors associated with positive microscopic margin include tumour occurrence, tumour volume, stage of tumour, types of surgery (amputation or limb-salvage) and types of pelvic resections. Local and distant recurrence rate were higher when margins were positive. But paradoxically the disease-specific death rate was lower in cases with positive margins. Conclusion: Factors that influence the oncologic outcomes include tumour volume, stage of tumour, types of surgery, histological diagnosis and grading. Microscopic margin was a prognostic factor for all three primary endpoints of this study, but was not statistically proven as an independent prognostic factor. The probability of achieving a clear microscopic margin in attempted wide resections was as low as 50% only, similar to a previous published experimental study. Internal hemipelvectomy provides significantly better disease-specific survival rate, hence justified with proper indication and selection of patients