Comparing the Outcomes of Neoadjuvant Versus Adjuvant Chemotherapy for
Osteosarcoma: A National Cancer Database Study
Abstract
Background: Neoadjuvant chemotherapy followed by surgery and subsequent
adjuvant chemotherapy, has been a mainstay of many osteosarcoma
treatment protocols. However, the overall survival benefit over surgery
and adjuvant chemotherapy is unclear. This study directly compares the
outcomes among these treatment groups using a large population in the
National Cancer Database. Methods: Patients with osteosarcoma in the
National Cancer Database (2004-2019) were stratified based on
chemotherapy and surgery timing (neoadjuvant and adjuvant vs
adjuvant-only chemotherapy). We used Kaplan-Meier curves to compare OS
in the unmatched population and in a propensity score matched cohort
that controlled for demographics, treatment, and tumor characteristic
differences. Univariate and multivariate analyses were also used to
predict the likelihood of positive margins among the population.
Chi-square tests were used to compare 30- and 90-day mortality among
treatment groups. Results: The study population included 4,659 patients:
3,733 neoadjuvant and 926 adjuvant-only chemotherapy regimens. Patients
who underwent neoadjuvant therapy had significantly longer survival in
the unmatched analysis (p<0.001), but this difference narrowed
when controlling for covariates in the matched cohort (p=0.64).
Mortality at 30 and 90 days was insignificant between treatment groups
in both the full and matched cohorts (p=0.3 and p=0.9 respectively).
Neoadjuvant chemotherapy regimens predominated with over 75%
utilization, but this rate remained constant during the 15-year study
period. Three- and five-year survival were relatively unchanged during
this period at 75% and 62.5% respectively. Factors significantly
associated with positive margins in the multivariate analysis included
adjuvant-only chemotherapy (OR=1.6, p<0.001), older age
(OR=1.01, p<0.001), female sex (OR=1.27, p=0.04), adjuvant
radiation (OR=4.96, p<0.001), and stage IVB tumors (OR=2.11,
p<0.001). Conclusions: Neoadjuvant chemotherapy did not increase
overall or short-term survival compared to adjuvant chemotherapy alone
in our study. However, neoadjuvant therapy was associated with fewer
positive margins at the time of surgery in this analysis.