AB007. Is phrenic nerve sparing worthwhile for phrenic-involved thymic epithelial tumors: a retrospective cohort study

Abstract

Background

To determine whether phrenic nerve (PN) sparing offers a worthwhile trade-off between functional preservation and oncologic safety compared with resection in PN-involved thymic epithelial tumors (TETs), and to establish an objective tool for postoperative respiratory risk stratification.

Methods

In this retrospective cohort of TETs with PN invasion, 122 propensity score–matched cases were analyzed from 2016 to 2024. PN preservation or resection was determined intraoperatively based on the extent of invasion. Diaphragmatic elevation (DE) ratio was calculated as [(preoperative diaphragm–apex distance − postoperative distance)/preoperative distance] × 100% according to X-rays, and cutoff values were defined by respiratory complication risk. Perioperative and oncologic outcomes were compared between PN-preservation and PN-resection groups.

Results

Overall perioperative morbidity and recovery outcomes were comparable between the PN-sparing and PN-resection groups. However, tumor progression was significantly more frequent following PN-sparing (39.3% vs. 23.0%), resulting in worse progression-free survival (P=0.03), although overall survival remained comparable. Multivariable analysis identified PN preservation as an independent predictor of progression (P=0.049). Furthermore, our ROC-derived DE classification (mild ≤15%, moderate 15%–25%, severe ≥25%) predicted severe postoperative respiratory complications (P<0.001).

Conclusions

PN resection improves progression-free survival without increasing severe perioperative complications, though overall survival remains comparable.

Figure 1.

Respiratory function and oncologic outcomes between PN-sparing and PN-resection groups. (A) Decline rates of FVC and FEV1 in PN-sparing (red) and PN-resection (blue) groups over short- and long-term follow-up. (B) Longitudinal changes in DE in both groups. (C) ROC curves of DE cutoff values for predicting respiratory complications (Cutoff-1 for all grade respiratory complications and Cutoff-2 for grade III-IV respiratory complications). (D) Distribution of DE severity categories (mild, moderate, severe) in PN-sparing and PN-resection cohorts. (E) PFS between two groups. (F) OS between two groups. DE, diaphragmatic excursion; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 second; OS, overall survival; PFS, progression-free survival; PN, phrenic nerve; ROC, receiver operating characteristic.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.