Incidence trends and factors affecting survival in thymic carcinoma: Insights from SEER data.

Abstract

e20169 Background: Thymic carcinoma is a rare neoplasm, accounting for less than 0.01% of new cancer diagnoses annually. It carries a poorer prognosis compared to its counterpart thymoma. This study aims to identify demographics, incidence trends, and factors affecting overall survival (OS) in thymic carcinoma. Methods: We performed a retrospective cohort analysis using the Surveillance, Epidemiology, and End Results (SEER) database, including patients diagnosed with thymic carcinoma from 2000 to 2022. Demographics and treatment data were summarized using descriptive statistics. Cox proportional regression analysis was used to identify factors impacting OS. Results: Between 2000 and 2022, a total of 7,309 patients were diagnosed with thymic carcinoma. The highest incidence occurred in patients under 60 years old at 43.6%. However, compared with patients under 60, those aged 60–69 had a 39% higher risk of death (HR = 1.39, 95% CI 1.27–1.52), and patients ≥70 had more than twice the risk. Males comprised 53.4% of cases, and Caucasians accounted for 66.1%. Most patients lived in urban areas (92.3%) and had an annual income >$60,000 (91.4%). Married patients (59.7%) had better OS than their unmarried counterparts. The incidence trends revealed a significant increase from 2000 to 2022. The incidence rates were: 16.4% (2000 -2005), 18.3% (2006 -2010), 19.5% (2011 - 2015), and 45.8% (2016-2022). However, the survival rates improved over time (See table). Regarding treatment, patients who received surgery and radiation were associated with better OS; interestingly, receipt of chemotherapy was not associated with better OS. Hazard ratios for all factors are summarized in the Table. Conclusions: This, the largest study to date on thymic carcinoma, demonstrates a rising incidence from 2000 to 2022 alongside improved OS. Patients diagnosed in the most recent period (2016–2022) had a restricted mean survival time of 15.02 years, indicating that, on average, they survived approximately 15 years within the study’s observation period, despite median survival not being reached due to too few events. These findings provide insights into the demographics and clinical factors influencing survival in this rare malignancy. Variable Group Hazard ratio Gender Male vs Female 1.19 (CI 1.11-1.28) Age 60-70 years vs <60 years 1.39 (CI 1.27-1.52) >70 years vs < 60 years 2.43 (CI 2.24-2.68) Year of diagnosis (2006-2010) vs (2000-2005) 0.91 (CI 0.83-1.00)* (2011-2015) vs (2000-2005) 0.93 (CI 0.83-1.03)* (2016-2022) vs (2000-2005) 0.84 (CI 0.75-0.94) Income <30K vs >60K 1.31 (CI 0.81-2.11)* 30-60K vs >60K 1.24 (CI 1.1-1.4) Race White vs Black 0.98 (CI 0.88-1.08)* Other vs Black 0.91 (CI 0.8-1.04) Marital status Yes vs No 1.22 (CI 1.14-1.31) Chemotherapy Yes vs No 1.91 (CI 1.7-2.05) Surgery Yes vs No 0.26 (CI 0.24-0.28) Radiation Yes vs No 0.83 (CI 0.77-0.89) p-value < 0.001 except for *non significant.