Abstract
Background Although tumor size is included in the definition of T descriptor in the tumor-node-metastasis
(TNM) classification of many solid tumors, it is not considered for thymomas. This
study aimed to assess the relationship of tumor diameters (the largest tumor diameter
[LTD] and the mean tumor diameter [MTD]) with survival in thymoma patients undergoing
surgical resection in a single center.
Methods The study included 127 thymoma patients (age, 49.2 ± 15.2 years; 65 males), who were
evaluated based on pathological tumor sizes according to the LTD and MTD ([largest
diameter + shortest diameter] / 2) and divided into three subgroups for each parameter
as: patients with an LTD of ≤5 cm, 5.1 to 10 cm, and >10 cm and patients with an MTD
of ≤5, 5.1 to 10, and >10 cm.
Results In thymoma patients, survival significantly differed according to the presence of
myasthenia gravis (p = 0.018), resection status (R0 or R1; p = 0.001), T status (p = 0.015), and the Masaoka–Koga stage (p = 0.003). In the LTD subgroups, the overall survival of those with R0 resection was
lower in those with an LTD of 5.1 to 10 cm than in those with an LTD of ≤5 cm (p = 0.051) and significantly lower in those with an MTD of 5.1 to 10 cm than in those
with an MTD of ≤5 cm (p = 0.027). In the MTD subgroups, survival decreased as the tumor size increased.
Conclusion Both smaller tumor size and complete resection are associated with better survival
in thymoma patients. Therefore, the largest or the mean tumor size might be considered
as a criterion in the TNM staging for thymoma.
Keywords
thymoma - tumor staging - tumor size - thymic epithelial tumors
