Objectives: Locally advanced thymoma can often involve the phrenic nerve (PN) due to its location on the mediastinal pleura. However, en bloc resection including the PN may cause severe postoperative complications, especially in myasthenia gravis patients. The aim of the study was to determine whether a PN involved could be spared during thymoma resection.
Methods: A retrospective study was conducted on patients who underwent resection of Masaoka Stage III and IV thymomas adherent, on digital palpation, to at least one PN in our institution between 1998 and 2012. An en bloc resection of the tumour with the invaded PN was performed unless patients with no preoperative PN paralysis had: both PN involved, compromised preoperative lung function, severe myasthenia gravis, severe comorbidities or minimal PN involvement (PN adherent to the edge of the tumour). All patients received postoperative radiation therapy.
Results: There were 114 patients with a mean age of 57 years (range, 28-84). PN was spared in 73 patients (64%) and removed in 41 (36%). Sixty-five patients had Masaoka Stage III (57%) and 49 had Stage IV (43%); these were similar between both groups. On permanent histology, 6 (15%) of the resected PN were not involved, whereas a permanent postoperative PN palsy was found in 4 (5.4%) patients where the PN was spared. Postoperative mortality and morbidity were 0 and 15% in the spared group and 2.4 and 9.7% in the resected group, respectively (P = 0.56). Recurrence rate was significantly higher in the spared group (39.5 vs 19.5%; P = 0.02) but the 5-year disease-free survival rates (53.6 vs 66.8%, P = 0.14) and overall 5-year survival (85 vs 88%, P = 0.6) were not significantly different between the spared- and resected-PN groups, respectively.
Conclusions: Sparing the PN during thymoma resection achieved good long-term and disease-free survivals in high-risk patients comparable with en bloc PN resection. However, it carried a higher risk of recurrence despite adjuvant radiation therapy.
Keywords: Mediastinal tumour; Phrenic nerve; Surgery; Thymoma.