Survival Trends and the Advanced-Stage Paradox in Osteosarcoma in Peru: A 15-Year Cohort Study (2008-2023)

Osteosarcoma is the most common primary malignant bone tumor in adolescents and young adults. Latin America has the poorest survival reflecting disparities in early diagnosis, referral pathways, and access to specialized cancer care. In Peru, national referral coverage for cancer has expanded over the past decade; however, whether this expansion has translated into earlier-stage diagnosis and improved survival remains unclear. We evaluated survival trends and prognostic factors for osteosarcoma in a national referral center, with a focus on stage at presentation as a marker of health system equity.

We conducted a retrospective cohort study of patients diagnosed with osteosarcoma between 2008–2023 at the National Institute of Neoplastic Diseases (INEN). Demographic, clinical and treatment data were collected. OS was estimated with Kaplan–Meier curves and compared using the log-rank test. Univariable and multivariable Cox models identified factors associated with mortality.

A total of 446 patients were included, with an increase in the number of diagnoses across periods (41 in 2008–2012, 80 in 2013–2017, and 325 in 2018–2023). Median OS was 24.1 months, and 12, 36, and 60-month OS rates were 67%, 41%, and 30%. The proportion of metastatic disease at presentation increased over time (21%, 34%, and 37% across the three periods). Adolescents and young adults aged 15–29 years had worse OS compared with children aged 0–14 years (18.6 vs 29.4 months). Stage IV disease was associated with markedly reduced survival (10.5 vs 34.3 months). In multivariable analysis, age 15–29 years (HR 1.34; 95% CI 1.03–1.73) and stage IV (HR 2.17; 95% CI 1.70–2.77) remained independent predictors of mortality.

Over 15 years, expansion of national referral coverage for osteosarcoma in Peru was accompanied by a paradoxical increase in advanced-stage presentation, highlighting persistent inequities in timely diagnosis and access to specialized care. These findings underscore the urgent need for focused interventions such as earlier detection strategies, streamlined referral pathways, and system level implementation approaches to reduce delays in diagnosis and improve survival in resource-limited settings.