Osteosarcoma: A sarcoma originating in bone-forming cells, affecting the ends of long bones. It is the most common and most malignant of sarcomas of the bones, and occurs chiefly among 10- to 25-year-old youths. (From Stedman, 25th ed)Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.Osteosarcoma, Juxtacortical: A form of osteogenic sarcoma of relatively low malignancy, probably arising from the periosteum and initially involving cortical bone and adjacent connective tissue. It occurs in middle-aged as well as young adults and most commonly affects the lower part of the femoral shaft. (Stedman, 25th ed)Femoral NeoplasmsCell Line, Tumor: A cell line derived from cultured tumor cells.Leg Bones: The bones of the free part of the lower extremity in humans and of any of the four extremities in animals. It includes the FEMUR; PATELLA; TIBIA; and FIBULA.Osteoblastoma: A benign, painful, tumor of bone characterized by the formation of osteoid tissue, primitive bone and calcified tissue. It occurs frequently in the spine of young persons. (From Dorland, 27th ed; Stedman, 25th ed)Humerus: Bone in humans and primates extending from the SHOULDER JOINT to the ELBOW JOINT.Tumor Cells, Cultured: Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.Osteoblasts: Bone-forming cells which secrete an EXTRACELLULAR MATRIX. HYDROXYAPATITE crystals are then deposited into the matrix to form bone.Sarcoma, Ewing: A malignant tumor of the bone which always arises in the medullary tissue, occurring more often in cylindrical bones. The tumor occurs usually before the age of 20, about twice as frequently in males as in females.Methotrexate: An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of TETRAHYDROFOLATE DEHYDROGENASE and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA.Chondrosarcoma: A slowly growing malignant neoplasm derived from cartilage cells, occurring most frequently in pelvic bones or near the ends of long bones, in middle-aged and old people. Most chondrosarcomas arise de novo, but some may develop in a preexisting benign cartilaginous lesion or in patients with ENCHONDROMATOSIS. (Stedman, 25th ed)Dog Diseases: Diseases of the domestic dog (Canis familiaris). This term does not include diseases of wild dogs, WOLVES; FOXES; and other Canidae for which the heading CARNIVORA is used.Doxorubicin: Antineoplastic antibiotic obtained from Streptomyces peucetius. It is a hydroxy derivative of DAUNORUBICIN.Gene Expression Regulation, Neoplastic: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in neoplastic tissue.Lung Neoplasms: Tumors or cancer of the LUNG.Cell Proliferation: All of the processes involved in increasing CELL NUMBER including CELL DIVISION.Antineoplastic Agents: Substances that inhibit or prevent the proliferation of NEOPLASMS.Neoplasm Metastasis: The transfer of a neoplasm from one organ or part of the body to another remote from the primary site.Apoptosis: One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.Amputation: The removal of a limb or other appendage or outgrowth of the body. (Dorland, 28th ed)Cisplatin: An inorganic and water-soluble platinum complex. After undergoing hydrolysis, it reacts with DNA to produce both intra and interstrand crosslinks. These crosslinks appear to impair replication and transcription of DNA. The cytotoxicity of cisplatin correlates with cellular arrest in the G2 phase of the cell cycle.Ifosfamide: Positional isomer of CYCLOPHOSPHAMIDE which is active as an alkylating agent and an immunosuppressive agent.