Is Phrenic Nerve Sparing Worthwhile for Phrenic-involved Thymic Epithelial Tumors?

Is Phrenic Nerve Sparing Worthwhile for Phrenic-involved Thymic Epithelial Tumors?


Objective: Thymic epithelial tumours (TETs) involve phrenic nerve (PN) in 10-30% of advanced cases. Surgeons frequently face the dilemma of whether to preserve or resect PN, balancing the potential benefits of functional preservation against oncologic advantage of more extensive tumor removal. The primary objective was to compare clinical outcomes between PN-preservation and PN-resection groups. Secondly, we propose a novel classification system of postoperative diaphragmatic elevation (DE).
Methods: In this retrospective cohort of TETs with PN invasion, 128 propensity score–matched cases were analyzed from 2016 to 2023. PN preservation or resection was determined intraoperatively based on the extent of invasion. DE ratio was calculated as [(preoperative diaphragm-apex distance − postoperative distance)/preoperative distance]×100%, according to chest X-rays, and cutoff values were defined by the receiver operating characteristic (ROC) analyses. Perioperative and oncologic outcomes were compared between PN-preservation and PN-resection groups.
Results: PN-sparing group had better preservation of postoperative pulmonary function in short term, with smaller declines in forced vital capacity and forced expiratory volume in one second. However, long-term pulmonary function was similar between groups. Longitudinal analysis of chest radiographs revealed distinct patterns: the PN-resection group exhibited progressive DE, peaking at 28% by 18 months postoperatively, whereas the PN-sparing group maintained stable. Importantly, a novel ROC-derived DE classification (mild ≤15%, moderate 15–25%, severe ≥25%) demonstrated strong predictive value for postoperative respiratory complications (P=0.004). Compared to PN-resection group, PN-sparing group had higher tumor progression rate (43.8% vs 23.4%), higher recurrence risk (P=0.031), and higher rate of pleural dissemination (37.5% vs 20.3%). The overall survival remained comparable between groups (P=0.126). Multivariable Cox analyses identified PN preservation (P=0.047) and incomplete resection (P=0.050) were independent predictors of tumor progression.
Conclusion: PN preservation provides short-term functional benefits but a higher risk of tumor progression. PN resection should be prioritized in cases of PN invasion to ensure complete resection and reduce recurrence. Our novel diaphragmatic elevation classification system provides an objective tool for postoperative respiratory risk stratification.

Wang Shuai (1), Junkan Zhu (2), Zhenyang Lin (3), Jiahao Jiang (4), Yongqiang Ao (5), Jianyong Ding (5), (1) Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, Shanghai, Shanghai, (2) Zhongshan Hospital, Fudan University, Shanghai, Shanghai, (3) Zhongshan Hospital, Fudan University, Xiamen, MN, (4) Fudan University Zhongshan Hospital, Shanghai, Shanghai, (5) Zhongshan hospital, Fudan university, Shanghai, NA