A Phase II Study of Partial and Subtotal Thymectomy for Thymoma (JART02)

We believe the merit of preservation of a part of the thymus following surgery for thymoma. We evaluated the efficacy of partial or subtotal thymectomy for early-stage thymoma in the prospective study.

The Japanese Association for Research on the Thymus conducted a multiple institutional study of thymectomy for thymoma localized in the thymus without total thymectomy. Patients without autoimmune disease who had an anterior mediastinal tumor that had been clinically diagnosed as an early-stage thymoma were enrolled in the study. Patients who were positive for anti-acetylcholine receptor antibodies were excluded.

Sixty-three patients were enrolled preoperatively; 27 patients were judged as being inappropriate based on the other thymic pathologies or tumor invasion. The remaining 36 cases were diagnosed as early-staged thymoma and analyzed. The mean age of the patients was 61 years. The mean maximal tumor diameter in the resected specimens was 3.6 cm. The most common pathological types of thymoma were AB (n = 10) and B1 (n = 10). The Masaoka stages were classified as stage I (n = 22) and II (n = 14). The mean observation period was 63 months. Two patients died due to respiratory dysfunction, which was not related to thymoma. One hundred percent of the patients remained recurrence-free.

This prospective study suggested the efficacy of partial or subtotal thymectomy for early-stage thymoma in patients without any apparent evidence of autoimmune disease. We can preserve a part of the thymus even following surgery for thymoma to prepare the possible second malignancies or diseases in future.