Early Masaoka stage and complete resection is important for prognosis of thymic carcinoma: a 20-year experience at a single institution.

Abstract

OBJECTIVE: Prognosis of primary thymic carcinomas is poor due to advanced stage progression at diagnosis and highly malignant behavior. We retrospectively evaluated patients with thymic carcinoma to determine the prognostic factors.

METHODS: Sixty patients diagnosed and treated for thymic carcinoma from 1986 to 2005 were reviewed retrospectively. Influences of demographic characteristics, Masaoka stage, histologic grade, completeness of resection and adjuvant treatment on survival were evaluated. We defined complete resection as macroscopically and microscopically total resection of a tumor (R0 resection) and incomplete resection was subdivided into microscopic incomplete resection (R1 resection) or macroscopically incomplete resection (R2 resection).

RESULTS: There were 42 male and 18 female patients and mean age was 53.9 (+/-14.4) years old. The 5-year overall survival rate was 38.8% and median survival time was 35.6 months. The most common histologic type was squamous cell carcinoma (n=29). In our study, 5 patients (8.3%) were in Masaoka stage I, 5 (8.3%) were in stage II, 19 (31.7%) were in stage III, 15 (25.0%) were stage in IVa, and 16 (26.7%) were in stage IVb. Among 40 patients who underwent surgical resection, complete resection was achieved in 14 patients. The 5-year survival rate after complete resection was 85.1% and was considered significantly better than those after incomplete resection (29.0%, p=0.001) and non-surgical treatment (16.7%, p<0.001). But, no survival difference could be found between the incomplete resection group and non-surgical treatment group (p=0.15). The 5-year survival rates of early Masaoka stage patients were significantly higher than advanced Masaoka stage (90.0% vs 28.3%, p=0.001). The recurrence rates within 3 years after R1 resection (75.0%) were significantly higher than that after R0 resection (14.9%, p=0.008).

CONCLUSIONS: In thymic carcinoma, complete resection of early Masaoka stage lesions is the most important factor for disease control and long-term survival of patients.