Thymoma: A multivariate analysis of factors predicting survival

Background. Despite complete surgical excision, malignant thymomas often recur with resultant death. We reviewed our series to determine which factors independently predict survival after surgical resection. Methods. A retrospective analysis of patients operated on for thymoma between 1949 and 1993 at Memorial Sloan-Kettering Cancer Center was performed. Clinical data were collected from chart review. Only patients with a pathology report confirming the diagnosis of thymoma were included in this analysis. Kaplan-Meier survival curves were generated and comparisons of survival analyzed by log rank test. Multivariate analysis was performed by the Cox proportional hazards model. Results. One hundred eighteen patients with thymoma underwent operation. There were 86 complete resections (73%), 18 partial resections (15%), and 14 biopsies (12%). By Masaoka staging, 25 patients were stage I (21%), 41 stage II (35%), 43 stage III (36%), and 9 stage IVa (8%). Overall survival was 77% at 5 years and 55% at 10 years. Tumor recurred in 25 (29%) of 86 completely resected thymomas. Stage of disease (p = 0.03) was the only independent prognostic factor affecting recurrence. By multivariate analysis, stage (p = 0.003), tumor size (p = 0.0001), histology (p = 0.004), and extent of surgical resection (p = 0.0006) were independent predictors of long-term survival. Conclusions. Patients with stage I disease require no further therapy after complete surgical resection. Neoadjuvant therapy should be considered for patients with large tumors and invasive disease.