From Bimodal to Unimodal: The Transformed Incidence of Osteosarcoma in the United States

Abstract

ABSTRACTBackgroundOsteosarcoma is the most common primary bone malignancy. It has classically been described as having a bimodal incidence by age, with the first peak in the second decade of life and the second peak after 65 years of age. We sought to identify whether the bimodal incidence distribution still exists for osteosarcoma using the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) and the National Inpatient Sample (NIS) (Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality) databases.MethodsIncidence rates of osteosarcoma between 1975-2020 were analyzed by age, year of occurrence, sex, race, and primary tumor site using the SEER program data. The age of maximum incidence in patients 40 years of age and older was analyzed by calendar year to observe for a consistent second peak. Fisher’s Exact test was also conducted with the SEER data to assess if there was a significant association between the occurrence of osteosarcoma in patients 35-64 years old and those 65+ years old. Incidence of tumors of the long bones of the lower limbs using ICD-9 and 10 diagnosis codes from the NIS discharge database 2012-2019 were also analyzed for comparison.ResultsA total of 1,779 cases of osteosarcoma were reported in the SEER database from 1975-2020. Across the 46 calendar year span, a consistent first peak appeared in the second decade of life alternating between the 10-14 and 15-19 age groups. In the 40+ cohort, the age of the highest incidence varied widely each calendar year: being found in age groups 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, & 85+ years old (5, 3, 5, 1, 2, 1, 2, 1, & 1 times respectively). For 25 years of the 46-year span, the max was shared by more than one age group. Overall, no single age group from the 40+ age group held a consistent maximum from 1975-2020.Using the NIS program and similar methodology, we analyzed 86,100 discharges of lower limb long bone tumors from 2012-2019 as a reference. The NIS data exhibited nearly identical patterns, with a unimodal incidence in adolescence and no obvious second peak.ConclusionOur analysis shows that the incidence of osteosarcoma is no longer bimodally distributed. This may be due to the increased use of bisphosphonates in recent years for the effective management of Paget’s disease, leading to a decline in late-age bone tumors. Our findings suggest the need to update our understanding of the epidemiology of osteosarcoma, as it should be considered more as a disease of adolescence with only sporadic incidence later on in older age.