Seung Hwan Song1, Jee Won Suh1, Woo Sik Yu1, Go Eun Byun1, Seong Yong Park1, Chang Young Lee1, Jin Gu Lee1, Dae Joon Kim1, Hyo Chae Paik1, Geun Dong Lee2, Se Hoon Choi2, Hyeong Ryul Kim2, Yong-Hee Kim2, Dong Kwan Kim2, Seung-Il Park2, Samina Park3, Yoohwa Hwang3, In Kyu Park3, Chang Hyun Kang3, Young Tae Kim3, Jong Ho Cho4, Hong Kwan Kim4, Yong Soo Choi4, Jhingook Kim4, Jae Il Zo4, Young Mog Shim4, Kyoung Young Chung1
1Department of Thoracic and Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea;2Asan Medical Center, Ulsan University College of Medicine, Seoul, Republic of Korea;3Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea;4Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
Correspondence to: Seung Hwan Song. Department of Thoracic and Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea. Email: lenierfree@yuhs.ac.
Background: For the Masaoka-Koga stage II and III thymoma, complete resection is a standard treatment. Postoperative radiotherapy (PORT) has been tried, but its role is controversial. We analyzed the data which were collected from four Korean hospitals to clarify the role of PORT in the stage II and III thymoma patients.
Methods: From January 2000 to December 2013, a total of 1,663 patients underwent operations for thymic tumors in the four Korean hospitals. Of those, patients who had thymic carcinoma, neuroendocrine tumor, Masaoka-Koga stage I and IV, and had absent data were excluded. The remaining 668 patients (527 stage II and 141 stage III) were included. Among them, 443 patients received PORT (335 stage II and 108 stage III). Propensity score matching (PSM) was performed and 404 patients (346 stage II and 58 stage III) were selected.
Results: Perioperative characteristics including age, sex, preoperative conditions, extent of surgery, WHO subtype, tumor size, R0 resection, and lymph node metastasis were not different between PORT group and no PORT group after PSM. The median follow up duration was 61.4 months (range, 0.3–182.4 months). In the survival analysis of stage II, PORT group showed no difference of both 5-year recurrence free survival (RFS) (95.9% vs. 96.8%, P=0.573) and 5-year overall survival (OS) (94.6% vs. 93.8%, P=0.839). But in the stage III, PORT group showed better trend of 5-year RFS (72.8% vs. 49.2%, P=0.067) and significant better 5-year OS (86.5% vs. 54.7%, P=0.008). In the multivariate Cox regression analysis in stage III, PORT was a significant positive prognostic factor for both RFS (P=0.011) and OS (P=0.004). But in stage II, it was not significant.
Conclusions: In this analysis, PORT could improve the RFS and OS in stage III thymoma patients, but in stage II thymoma patients, it couldn’t show survival benefit.
Keywords: Postoperative radiotherapy; Korea Association for Research on the Thymus; propensity score matching; thymoma
