Impact of Age on Long-Term Mortality and Net Survival Benefit of Radiotherapy for Early-Stage Follicular Lymphoma from the SEER Database (2000-2015)

Abstract

<h3>Purpose/Objective(s)</h3> This study's aim was to analyze the effect of age on long-term mortality and the net survival benefit of radiotherapy (RT) for early-stage follicular lymphoma (FL). <h3>Materials/Methods</h3> A total of 8,803 patients with early-stage FL in the Surveillance, Epidemiology, and End Results (SEER) database (2000-2015) were identified for this study. Primary therapy included RT (27.0%), chemotherapy (CT, 29.3%), observation (24.1%), and other/unknown treatments (19.6%). Relative survival (RS), the standardized mortality ratio (SMR), and transformed Cox regression were used to compare survival differences between treatments. <h3>Results</h3> The risk of dying from FL than other causes over time was higher among younger patients (¡Ü60 years) and within 5 years among older patients (>60 years), who had a higher risk of dying from FL beyond 5 years. Overall survival (OS) rates continuously decreased regardless of treatment; the survival difference widened between RT and non-RT over 10 years. The RS rates for RT remained high (∼95%) over 10 years, but progressively decreased for other treatments. RT had significantly higher 10-year OS (77.2%) and RS (96.1%), but lower SMR (1.77), compared with CT (65.2%; 82.6%; 2.92; Ps < 0.001), observation (65.5%; 90.1%; 2.18; Ps < 0.001), and other/unknown treatments (66.5%, P < 0.001; 89.9%, P = 0.136; 2.05, P < 0.001). RT was an independent predictor of better RS and OS (P < 0.001). No significant interaction between age and RT was identified for RS (Pinteraction = 0.305) or OS (Pinteraction = 0.272), indicating similar survival benefits among patients of all ages. <h3>Conclusion</h3> RT provides significant long-term net survival benefits in early-stage FL, and remains a mainstay first-line treatment for early-stage FL.