AB058. Surgical management of TNM stage IVA thymoma and thymic carcinoma: the network TYME experience (4TYMEs)

Background: Tumor-node-metastasis (TNM) stage IVA thymic epithelial tumors (TETs) are rare and pose significant challenges due to limited and heterogeneous data. A major difficulty in managing stage IVA disease is the lack of clarity on the optimal treatment approach, particularly concerning the role of surgery, which remains controversial. This study aimed to evaluate clinical characteristics, pathological findings, and oncological outcomes in a consecutive cohort of surgically treated patients from the referring centers of the ThYmic MalignanciEs (TYME) Italian Network. Methods: Patients with pathologically confirmed stage IVA TETs undergoing surgery were retrospectively reviewed from the TYME Network database. Demographic, clinical, and histopathological variables were analyzed, including prior cancer, autoimmune disease, Eastern Cooperative Oncology Group (ECOG) and American Society of Anesthesiologists (ASA) scores, histologic subtype, resection status, and use of perioperative treatments. Survival outcomes were estimated using Kaplan-Meier analysis, and predictors of recurrence-free survival (RFS) and overall survival (OS) were explored through univariable and multivariable methods. Results: Fifty patients were enrolled. The median age was 51 years; 64% were male. All patients underwent surgery with curative intent; R0 resection was achieved in 73.3%. The most common histotypes were B2 (22%), B1 (20%), B3 (16%), and squamous thymic carcinoma (16%). Preoperative chemotherapy was administered to 45% of patients, postoperative radiotherapy to 42% of patients. Median OS was 122.9 months (Figure 1). There was no significant survival difference by resection margin (P=0.68) or preoperative chemotherapy (P=0.74). Median disease-free interval from the first surgery was 18 months (range, 1–181 months). R0 patients showed longer mean RFS (28.3 months) than R1-R2 (19.0 months), but the difference was not statistically significant. Histologic subtype was strongly associated with RFS (P=0.03). B1 thymoma had the longest RFS (61 months), significantly longer than thymic carcinoma (6.6 months, P=0.03). In multivariable analysis, histologic type and tumor volume were independent predictors of RFS (P<0.001 and P=0.03, respectively). Conclusions: Surgical resection in TNM stage IVA TETs is feasible and can achieve long-term survival in selected patients within a multimodal treatment strategy. Histologic subtype is a key determinant of both recurrence risk and survival. These findings support surgery as a critical component of multimodal therapy, with histopathology and tumor volume guiding postoperative management and follow-up strategies.