A systematic review of paraneoplastic syndromes associated with thymoma: Treatment modalities, recurrence, and outcomes in resected cases.

Objective: Paraneoplastic syndromes associated with thymomas remain incompletely understood. The objective was to examine the association between surgically resected thymomas and paraneoplastic syndromes over the past half century. Methods: A primary PubMed/MEDLINE search was used to identify published articles describing paraneoplastic syndromes associated with thymomas from 196o to 2019. A secondary search identified additional articles referenced in the articles found in the primary search. Kaplan-Meier and log-rank test were used for timeto-event data analyses. Results: From 407 articles describing 507 patients,123 different paraneoplastic syndromes were associated with thymoma. The 5 most common paraneoplastic syndromes were myasthenia gravis, pure red cell aplasia, lichen planus, Good syndrome, and limbic encephalitis. Complete or partial resolution of paraneoplastic syndrome symptoms after surgery was noted in 76% of patients, of whom 21% had a relapse or new paraneoplastic syndrome onset after surgery. The most common adjunctive therapy associated with resolution of paraneoplastic syndrome was corticosteroids (30%). For all patients after surgery, thymoma recurrence was observed in 17% of cases, whereas recurrence of paraneoplastic syndrome was observed in 34% of cases, and both were observed in approximately 17% of cases. The 5- and 10-year overall survivals were 78% and 66%, respectively. Improved overall survival was associated with patients who had total resolution from paraneoplastic syndrome. Conclusions: A comprehensive assessment of publications over the past half century suggests that a multimodal treatment approach that includes surgical resection of thymomas is able to achieve paraneoplastic syndrome resolution in a majority of patients. Onset of new paraneoplastic syndromes after surgery is associated with the recurrence of the first paraneoplastic syndrome, and resolution of paraneoplastic syndrome is associated with improved overall survival.