You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["AnatomicalEntity"].

Please return the output as a JSON object of the format: {"AnatomicalEntity": ["tumor cells", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Postoperative progression of pulmonary metastasis in osteosarcoma.
Early relapse with distant metastasis often is observed in patients with cancer after resection of the primary tumor. It is considered that resection of the primary tumor induces activation of systemic angiogenesis and enhances progression of remote metastasis. The authors show that resection of the primary osteosarcoma tumor enhances progression of pulmonary metastasis in animal osteosarcoma models. Matrigel plug neovascularization assay revealed that systemic angiogenic activity was elevated after primary tumor removal (tumor intact group, 1.61 +/- 0.21 g/dL; tumor removed group, 4.92 +/- 0.35 g/dL). In addition, serum concentration of the angiogenesis inhibitor, endostatin, decreased significantly after primary tumor removal. Treatment with the antiangiogenic reagent TNP-470 suppressed postoperative progression of pulmonary metastasis. These results indicate the possibility that activation of angiogenic activity after resection of osteosarcoma tumors enhances progression of pulmonary metastasis. The current data also suggest that administration of antiangiogenic reagents can prevent progression of pulmonary metastasis in osteosarcoma postoperatively.
{"AnatomicalEntity": ["osteosarcoma", "primary osteosarcoma tumor", "pulmonary", "primary tumor", "cancer", "tumor", "serum", "osteosarcoma tumors"]}