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.

中文翻译：

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淋巴结清扫对胸腺恶性肿瘤的影响：多机构倾向评分匹配分析

简介：手术切除是胸腺恶性肿瘤的标准治疗方法。然而，淋巴结转移和淋巴结清扫的预后意义仍不清楚。本研究的目的是确定淋巴结转移的预后意义和淋巴结清扫 (LND) 在胸腺恶性肿瘤中的作用。方法：2000 年至 2013 年间，1597 名因胸腺恶性肿瘤接受胸腺切除术的患者纳入研究。评估淋巴结转移的预测因素和 LND 的预后意义。患者分为两组：（1）LND+组，有意LND（446例，27.9%）；(2) LND-组，无故意 LND（1151 例，72.1%）。在两组之间进行倾向评分匹配。结果：298 名胸腺瘤患者中有 20 名 (6.7%) 和 47 名 (31. 7%) 的 148 名胸腺癌患者。在多变量分析中，胸腺癌（风险比：19.2，p < 0.001）和肿瘤大小（风险比：1.09，p = 0.02）是淋巴结转移的重要预测因素。pN1 和 pN2 的 10 年无复发率显着低于 pN0（p < 0.001）。LND 不会增加手术死亡率或并发症。LND+ 和 LND- 组之间的 10 年无复发率无显着差异（胸腺瘤为 82.4% 与 80.9%，p = 0.46；胸腺癌为 45.7% 与 44.0%，p = 0.42）。结论：淋巴结转移是胸腺恶性肿瘤的重要预后因素。虽然 LND 没有改善胸腺恶性肿瘤的长期预后，但 LND 在准确分期和改善预后预测方面发挥了作用。