N. K. Yuen1, C. Li1, R. Bold1, A. Monjazeb1, D. Borys1, R. Canter1 1University Of California – Davis,Surgical Oncology,Sacramento, CA, USA
Introduction:
Radiation therapy (RT) is a standard component in the multimodality management of soft tissue sarcoma (STS), although increasing studies are focusing on the selective implementation of this modality. We hypothesized that the effects of RT would be influenced by age, potentially contributing to differences in treatment outcome. We sought to evaluate the effect of age on RT in a national database of STS patients.
Methods:
Using the Surveillance Epidemiology and End Results registry (1990-2011), we identified 30,898 adult patients (>18) with non-metastatic STS of major histologies undergoing surgery with or without RT. We compared patient demographics, tumor characteristics, and treatments by age. Multivariable analyses were used to examine the effect of these variables on overall (OS) and disease-specific survival (DSS). Hazard ratios were calculated based on multivariable Cox proportional hazards models.
Results:
The mean age at diagnosis was 54.9 years old. 31.5% of patients were ≥ 65 years old. 47.5% of patients were male, and 66.6% were white. Histologic grade was 32.4% high, 12.9% intermediate, 13.5% low, and 41.3% unknown. Leimoyosarcoma was the most common histology (27.9%), and extremity was the most common tumor site (37.4%). 70.2% of patients underwent surgery alone, 25.1% received adjuvant RT, and 4.7% neoadjuvant RT. On multivariable analysis, gender, year of diagnosis, histology, grade, size, marital status, and RT modality predicted OS, while year of diagnosis, ethnicity, histology, site, grade, RT, size, and marital status predicted DSS. The hazard ratio (HR) for OS was 1.11 (95% CI 1.02-1.21) and DSS was 1.13 (95% CI 1.03-1.25) comparing neoadjuvant to adjuvant RT in all age groups. In patients < 65 years old, the HR for OS was 1.23 (95% CI 1.09-1.39) and DSS was 1.24 (95% CI 1.10-1.39) for neoadjuvant to adjuvant RT. For patients ≥ 65, the HR for OS was 0.98 (95% CI 0.85-1.13), and DSS was 0.99 (95% CI 0.83-1.17) for neoadjuvant to adjuvant RT.
Conclusions:
Adjuvant RT was associated with superior oncologic outcome compared to neoadjuvant RT among STS patients undergoing surgical resection. The negative effect of neoadjuvant RT was exaggerated in younger patients, suggesting an age-related effect of RT. Further investigation into the etiology of this age-related association is indicated.