Registry-Based Analysis of Pediatric Osteosarcoma Characteristics in Puerto Rico

Despite therapeutic advances, pediatric osteosarcoma (OS) outcomes remain shaped by systemic disparities in access to timely diagnosis and specialized care. In Puerto Rico, where pediatric OS services are centralized and off-island referrals are common, these challenges are magnified. No prior study has documented the demographic or clinical characteristics of this population. This retrospective cohort study analyzed 44 patients under 21 years of age diagnosed with OS using data from the Puerto Rico Central Cancer Registry and the UPR Pediatric Hospital (HOPU). Variables included region of residence, insurance type, tumor site, metastasis at diagnosis, percentage of tumor necrosis, amputation status, Li-Fraumeni syndrome, treatment location, and survival. Tumor sites were overwhelmingly involved in long bones (84%), with the lower extremities representing 80% of cases, predominantly in the distal femur and proximal/distal tibia. No vertebral primaries were identified. Upper extremity tumors accounted for 13.6%, while craniofacial involvement (mandible) represented 6.8%. Although 61% of patients had private insurance, 54% underwent surgical treatment in the U.S, indicating that financial coverage does not necessarily compensate for limited local pediatric orthopedic oncology capacity. Among those treated off-island, 31% received care at St. Jude Children’s Research Hospital and 23% at other high-volume U.S centers, reflecting the need for complex limb-salvage infrastructure. Attempts at limb-salvage were documented, yet many ultimately required amputation, contributing to an overall amputation rate of 80% markedly higher than contemporary U.S. standards. At diagnosis, 26% presented with metastatic disease, predominantly pulmonary (64%). Tumor necrosis was heterogeneous, with 25% showing <50% necrosis, while some patients exhibited a favorable necrosis response; however, incomplete pathology documentation limited systematic interpretation. Li-Fraumeni syndrome was identified in 11% of OS patients, underscoring the need for strengthened hereditary cancer evaluation. Geographic clusters in the Northeast (20%) and Southeast (20%) likely reflect proximity to major metropolitan medical centers rather than true incidence variation. Mortality reached 20%, and recurrence occurred in 23% of patients. A major limitation is the loss of longitudinal clinical data after off-island transfer due to non-interoperable record systems. As the first registry-based analysis of pediatric OS in Puerto Rico, these findings reveal substantial structural barriers despite high insurance coverage. Future work will incorporate patient family-based surveys and interviews with local pediatric orthopedic surgeons to assess travel burden, diagnostic delays, and drivers of off-island surgical care, guiding equitable improvements in pediatric OS in PR. Citation Format: MiaSara Pérez Salvá, Rocio Krystal Rivera-Valentin, Celinés Rodriguez, Liliana Marie Castro-Jimenez. Bridging data gaps in pediatric osteosarcoma: The first registry-based analysis of Puerto Rican cases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7882.