Yoohwa Hwang1, Chang Hyun Kang2, Samina Park3, Hyun Joo Lee3, In Kyu Park3, Young Tae Kim3, Geun Dong Lee4, Hyeong Ryul Kim4, Se Hoon Choi4, Yong-Hee Kim4, Dong Kwan Kim4, Seung-Il Park4, Sumin Shin5, Jong Ho Cho5, Hong Kwan Kim5, Yong Soo Choi5, Jhingook Kim5, Jae Il Zo5, Young Mog Shim5, Chang Young Lee6, Jin Gu Lee6, Dae Joon Kim6, Hyo Chae Paik6, Kyung Young Chung6. 1. Department of Thoracic and Cardiovascular Surgery, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Republic of Korea. 2. Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: chkang@snu.ac.kr. 3. Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea. 4. Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University College of Medicine, Seoul, Republic of Korea. 5. Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 6. Department of Thoracic and Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
Abstract
INTRODUCTION: Surgical resection is a standard treatment for thymic malignancies. However, prognostic significance of nodal metastases and lymph node dissection remains unclear. The aim of this study is to determine prognostic significance of nodal metastases and the role of lymph node dissection (LND) in thymic malignancies. METHODS: Between 2000 and 2013, 1597 patients who underwent thymectomy due to thymic malignancy were included. Predictive factors for nodal metastasis and prognostic significance of LND were evaluated. Patients were divided into two groups: (1) LND+ group, with intentional LND (446 patients, 27.9%); and (2) LND- group, without intentional LND (1151 patients, 72.1%). Propensity score matching was performed between the two groups. RESULTS: Lymph node metastasis was identified in 20 (6.7%) of 298 patients with thymoma and 47 (31.7%) of 148 patients with thymic carcinoma. In multivariable analysis, thymic carcinoma (hazard ratio: 19.2, p < 0.001) and tumor size (hazard ratio: 1.09, p = 0.02) were significant predictive factors for lymph node metastasis. The 10-year freedom from recurrence rate of pN1 and pN2 was significantly worse than that of pN0 (p < 0.001). LND did not increase operative mortality or complication. There was no significant difference in 10-year freedom from recurrence rate between LND+ and LND- groups (82.4% versus 80.9%, p = 0.46 in thymoma; 45.7% versus 44.0%, p = 0.42 in thymic carcinoma). CONCLUSIONS: Lymph node metastasis was a significant prognostic factor in thymic malignancies. Although LND did not improve long-term outcomes in thymic malignancies, LND played a role in accurate staging, and improved prediction of prognosis.
INTRODUCTION: Surgical resection is a standard treatment for thymic malignancies. However, prognostic significance of nodal metastases and lymph node dissection remains unclear. The aim of this study is to determine prognostic significance of nodal metastases and the role of lymph node dissection (LND) in thymic malignancies. METHODS: Between 2000 and 2013, 1597 patients who underwent thymectomy due to thymic malignancy were included. Predictive factors for nodal metastasis and prognostic significance of LND were evaluated. Patients were divided into two groups: (1) LND+ group, with intentional LND (446 patients, 27.9%); and (2) LND- group, without intentional LND (1151 patients, 72.1%). Propensity score matching was performed between the two groups. RESULTS: Lymph node metastasis was identified in 20 (6.7%) of 298 patients with thymoma and 47 (31.7%) of 148 patients with thymic carcinoma. In multivariable analysis, thymic carcinoma (hazard ratio: 19.2, p < 0.001) and tumor size (hazard ratio: 1.09, p = 0.02) were significant predictive factors for lymph node metastasis. The 10-year freedom from recurrence rate of pN1 and pN2 was significantly worse than that of pN0 (p < 0.001). LND did not increase operative mortality or complication. There was no significant difference in 10-year freedom from recurrence rate between LND+ and LND- groups (82.4% versus 80.9%, p = 0.46 in thymoma; 45.7% versus 44.0%, p = 0.42 in thymic carcinoma). CONCLUSIONS: Lymph node metastasis was a significant prognostic factor in thymic malignancies. Although LND did not improve long-term outcomes in thymic malignancies, LND played a role in accurate staging, and improved prediction of prognosis.