The potency of curative-intent treatment for advanced thymic carcinoma

Heterogenous clinical or biological features are characteristic of thymic carcinoma. Well-defined clinical entities remain unclear because of rarity. The aim of this study was to clarify disease profiles, outcomes, and prognostic factors for survival among patients diagnosed with thymic carcinoma.

A retrospective review was conducted of the medical records of 68 thymic carcinoma patients among 187 patients diagnosed with thymic epithelial tumors between 1980 and 2013 in our institution. Clinical demographics, histology, overall survival, and factors expected to predict survival were analyzed. Differences in survival were assessed using Kaplan-Meier analysis and uni- and multivariate Cox proportional hazards regression analyses.

The study included 38 males (55.9%) and 30 females (44.1%). The median age at diagnosis was 63.5 years. The most common subtypes of thymic carcinoma were squamous cell carcinoma (69.1%), neuroendocrine carcinoma (16.2%), and mucoepidermoid carcinoma (5.9%). Masaoka-Koga staging of the 68 patients demonstrated no patients (0%) in Stage I, 3 (4.3%) in Stage II, 14 (20.6%) in Stage III, 12 (17.6%) in Stage IVa, and 39 (57.4%) in Stage IVb. The median survival time for all stages was 36.4 months (95% confidence interval 23.7-56.4); those for stages II, III, IVa, and IVb were: not reached, 65.8, 24.6, and 27.3 months, respectively. The difference by Masaoka-Koga staging was significant (p = 0.04). Overall survival rates at 1-, 5-, and 10-year were 76.3%, 36.0%, and 6.2%, respectively. By univariate analyses, the only favorable prognostic factor for overall survival was surgical intervention (p = 0.03), and, for Stage IVb, lymphatic metastasis without distant metastasis. However, clinically interesting variants did not differ significantly for predicting survival.

Surgical intervention results in better survival of thymic carcinoma, even in Stage IVb. The survival value of administration of curative-intent radiotherapy, or of identification of "resectability" in Stage IVb patients must continue to be discussed.