<p>Use Of Microwave Thermal Ablation In Management Of Skip Metastases In Extremity Osteosarcomas</p>

Abstract

BackgroundThe objective of this study was to evaluate the efficiency and safety of microwave thermal ablation in the treatment of skip metastases in extremity osteosarcomas. Osteosarcoma of extremities with skip metastases has a poor prognosis, and thus, microwave thermal ablation presents an attractive minimally invasive option in this patient group.MethodsA retrospective review included a cohort of 76 patients with extremity osteosarcoma in one institute, of which five cases (6.6%) showed skip metastases. Skip lesions located in proximal femur and primary sites were distal femur in all five patients. The authors treated skip lesions using microwave thermal ablation after primary tumors were removed at wide margins. Procedural efficacy and safety were determined with postoperative MSTS score and follow-ups of 12–62 months (median 22 months).ResultsThe ablation time was five to nine minutes (mean seven minutes). Taking advantage of Microwave-induced hyperthermia, wide resections of distal femur and endoprosthesis reconstructions were performed instead of total femoral resection and replacement in four patients, and above-knee amputation was performed instead of hip disarticulation in one patient. The postoperative hip functions were intact and the mean lower extremity MSTS score was 26. Three patients died at 12–22 months after definitive surgery because of pulmonary metastases, and two patients remained disease-free at 44 and 62 months after surgery, respectively. No local recurrence either at sites of primary tumors or skip lesions was found at time of the latest follow up.ConclusionMicrowave thermal ablation is efficacious in treating skip metastases of osteosarcoma in extremities. The modality has promise for good local control of tumors, less invasive surgeries, and intact and satisfied lower extremity functions in these relatively poor prognosis patients.Level of evidenceTherapeutic Level III.

Metastatic Progression of Osteosarcomas: A Review of Current Knowledge of Environmental versus Oncogenic Drivers

“…Skip metastasis can be single or multiple, distal, or proximal to the primary tumor. They are found in 1.4% to 10% of patients and are best seen on MRI [ 17 , 18 , 19 , 20 , 21 , 22 ]. According to the American Joint Committee on Cancer staging system for primary malignant bone tumors, patients with a discontinuous tumor in the primary bone site with no regional lymph node or other distant metastasis are considered at stage 3, whereas the presence of lung metastasis is considered stage 4a, and the presence of distant bone metastases or other organ metastases is considered stage 4b.…”

“…Independent prognostic factors for patients with synchronous lung metastases are the possibility of complete metastasectomy and the response to chemotherapy [ 26 ]. Recent studies reported that 45% of patients with skip metastasis survived after 5 years, the prognosis being better with skip metastases in the same bone versus trans-articular skip metastases [ 3 , 18 , 19 , 22 ].…”

Clinical Guideline for Microwave Ablation of Bone Tumors in Extremities

“…S kip metastasis in the medullary cavity of osteosarcoma has an incidence ranging from 1.4% to 10% 17,[59][60][61] , which often indicates poor prognosis 17,61 . After resection of osteosarcoma of the distal femur, a microwave ablation needle was placed into the medullary cavity to melt skip metastases in the medullary cavity, and then tumor curettage was performed.…”

“…No local recurrence was found in these five patients; three patients died of distant metastasis, and the remaining two patients survived. This technique prevents total femoral replacement and retains good limb function 17 .…”

“…From the initial stage of treating primary malignant bone tumors, the treatment has also been used to treat metastatic bone tumors, malignant soft tissue tumors, and benign bone tumors; moreover, the operation and operating technology have become increasingly standardized. Microwave ablation can be used as an independent percutaneous minimally invasive treatment for some benign bone tumors and bone metastases 13,14 , or as an auxiliary treatment for hemostasis, tumor inactivation or improving the safety of tumor resection boundary [15][16][17][18][19] .…”