Jae Kwang Yun1, Hyeong Ryul Kim1, Geun Dong Lee1, Su Kyung Hwang1, Se Hoon Choi1, Yong-Hee Kim1, Dong Kwan Kim1, Seung-Il Park1, Jae Jun Jung2, Sumin Shin2, Jong Ho Cho2, Hong Kwan Kim2, Yong Soo Choi2, Jhingook Kim2, Jae Il Zo2, Young Mog Shim2, Samina Park3, Kwan Yong Hyun3, Yoohwa Hwang3, Hyun Joo Lee3, In Kyu Park3, Chang Hyun Kang3, Young Tae Kim3, Chang Young Lee4, Jin Gu Lee4, Hyo Chae Paik4, Dae Joon Kim4, Kyoung Young Chung4
1Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University College of Medicine, Seoul, Republic of Korea;2Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School 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, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
Correspondence to: Jae Kwang Yun. Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University College of Medicine, 88, Olympic-ro 43-gil, 081, Seoul, Republic of Korea. Email: janies@nate.com.
Background: In spite of the clinical utility of tumor size, few studies have focused on the relationship between tumor size and oncological outcome in thymic epithelial tumors (TETs). This study is aimed to clarify the prognostic value of the tumor size after complete resection of TETs after the stratification of limited and advanced tumor stage.
Methods: Clinical records of patients who underwent R0 resection for TETs were retrospectively collected from four tertiary centers between January 2000 and February 2013. All of 1,291 patients had information about Masaoka-Koga stage (M-K group), whereas 445 of them could be classified by the 8th TNM staging system (TNM group). We defined the whole stage of TETs with limited stage and advanced stage based on the criteria whether they confined within the surrounding fatty tissues without invasion.
Results: The median tumor size was 6.0±2.8 and 6.5±3.0 cm in M-K group and TNM group. According to the definition of current study, limited stage of TETs (M-K stage I/II or TNM stage I) was shown to have smaller tumor size than advanced stage with statistically significance in M-K group (5.8±2.7 vs. 7.2±3.0, Pvs. 7.2±3.1, P=0.003). In multivariate analysis, tumor size was found to be an independent prognostic factor for overall survival (OS) and freedom from recurrence (FFS) in limited stage (M-K group: P=0.004 for OS and 0.011 for FFR, TNM group: P=0.004 for OS and FFR), while it was not significant in advanced stage. Optimal cut-off value for tumor size was >5.5 cm for both OS and FFS, which statistically significant differences were shown in survival analysis according to the value.
Conclusions: Tumor size is the major determinant of prognosis for OS and FFR in limited stage TETs, such as breast and lung cancer without nodal involvement. The cut-off value >5.5 cm might be criteria for subdividing the 8th TNM stage I and help clinicians decide adjuvant treatment and proper surveillance.
Keywords: Thymic malignancy; tumor size; risk factor; oncological outcomes
