Malignant Local Seeding in Procedure Tracts of Pleural Mesothelioma: Incidence and Novel Risk Factors in 308 Patients.

Background/Objectives: Unlike other thoracic malignancies, seeding malignant cells along surgical tracts is a known complication of invasive diagnostic or therapeutic procedures for pleural mesothelioma (PM). We report the tract dissemination rate and risk factors in 308 consecutive patients treated over 9 years in a single institution who underwent pleurectomy decortication (PD). Methods: Clinical and outcome data were reviewed. Fisher's exact test, Kaplan-Meier estimators, and log-rank tests were used to identify significant risk factors for surgical tract dissemination and to compare overall survival. Results: There were 233 males (75.6%), 187 right-sided operations (61%), 190 (61.7%) epithelioid histology cases, and the median age was 69 (29-84). During the study, malignant cell dissemination in resected surgical tracts was diagnosed in 69 (22.4%) patients. The dissemination rates in epithelioid, biphasic, and sarcomatoid tumors were 24.7%, 20.4%, and 0%, respectively. Disseminated malignant surgical tract was associated with advanced nodal status (p = 0.001), advanced staging by the American Joint Committee on Cancer (AJCC 8th edition, p = 0.03), female sex (0.02), side of surgery (p = 0.03), and the number of video-assisted thoracoscopic surgery (VATS) ports (p = 0.003). In epithelioid mesothelioma, the median survival from diagnosis was 19.7 months in patients with tract seeding versus 36.3 months in patients without seeding (hazard ratio, 1.9; p = 0.001). Conclusions: Procedure tract dissemination occurs in almost every fourth patient with pleural mesothelioma and is associated with shorter overall survival in the epithelioid subtype.