AB012. OA02.03: Adjuvant chemotherapy improved survival of completely resected thymic squamous cell carcinoma

Background: To evaluate the efficacy of adjuvant chemotherapy for completely resected squamous thymic carcinoma.

Methods: Between 2009 and 2015, 196 consecutive patients who were diagnosed with squamous thymic carcinoma were collected. Patients of non-surgery, non-complete resection, neo-adjuvant therapy and those of Masaoka-Iva stage were excluded from the study. Clinical data were reviewed. Outcome measures included overall (OS) and freedom from recurrence (FFR). In all, 106 patients of completely resection were enrolled in this retrospective study.

Results: The median age was 56 years (range, 25–80 years). The clinical stage distribution according to the Masaoka system of I, II, III and IVb were 2 (2%), 37 (35%), 52 (49%), 15 (14%). Sixty-seven patients received adjuvant chemotherapy and 97 patients received adjuvant radiotherapy. With a median follow-up period of 56 months (range, 25–116 months), 31 patients died from disease. Forty-eight patients developed metastases, with a higher proportion (80%) in Masaoka stage IVb. The most common metastatic sites were lung (n=19). Two patients developed mediastinal relapse. The median freedom from relapse (FFR) was 26 months. Five-year overall survival (OS) and FFR were 68.4% and 52.8%. Masaoka stage was the only prognostic factor both for OS and FFR. Adjuvant chemotherapy remained associated with improved FFR in stage III of 52 patients (P=0.017) and a trend with OS (P=0.059). FFR in patients of stage II receiving four cycles of adjuvant chemotherapy was superior to that in patients not receiving adjuvant chemotherapy (P=0.041). Adjuvant chemotherapy for stage II and III squamous thymic carcinoma was statistically significantly associated with lower proportion of metastasis (P=0.038).

Conclusions: Completely resected squamous thymic carcinoma showed a relative good long-term survival. Advanced Masaoka stage was associated with shorter survival, especially for stage IVb. Adjuvant chemotherapy demonstrated improved outcomes in Masaoka stage II and III.

Keywords: Thymic carcinoma; complete resection; chemotherapy