The goal of this pilot study is to learn about patients with newly diagnosed osteosarcoma of an extremity, and whether surgically removing the tumor prior to the administration of any chemotherapy will improve functional outcomes. In order to learn about the patient's experience, the study team will administer questionnaires to the patient and surgeon at various timepoints to assess recovery and the function of the extremity.

This prospective, non-randomized pilot study will assess patient-reported functional outcomes of upfront surgical resection in patients with newly diagnosed, biopsy-proven, localized osteosarcoma of the extremity or the pelvis. Following biopsy, all patients will undergo wide excision of the tumor followed by systemic multi-agent cytotoxic chemotherapy consisting of a regimen at least equivalent to the standard of care of high dose Methotrexate, Doxorubicin, and Cisplatin (MAP). Patients and/or their parent/guardian will be administered PROMIS (Patient-Reported Outcomes Measurement Information System) questionnaires, while surgeons will be administered the Musculoskeletal Tumor Society (MSTS) questionnaire at various timepoints through the first year post-surgery.

Inclusion Criteria:

• Patients must have newly diagnosed, previously untreated, localized, high-grade osteosarcoma of an extremity (verified by histopathology) with plans to undergo upfront surgical resection of the tumor followed by systemic chemotherapy.
• Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1, or 2 (Karnofsky will be used for patients >16 years of age and Lansky score for patients <= 16 years of age)

Exclusion Criteria:

• Patients with metastatic disease at diagnosis
• Initiation of systemic therapy prior to enrollment
• Prior history of cancer
• Prior radiation therapy
• Active life-threatening infection
• Pregnancy (negative pregnancy test result must be obtained for female patients of childbearing potential)

Patients with newly diagnosed osteosarcoma with plans to undergo an upfront surgical resection of their tumor.