A real-world cohort study comparing chemotherapy and surgery in the treatment of stage IVA thymomas with pleural dissemination.

BACKGROUND

Chemotherapy is the guideline-recommended first-line therapy for stage IVA thymomas (TMs) with pleural dissemination, but its efficacy has never been specifically assessed. We aim to evaluate the efficacy of chemotherapy, and to compare the results of surgery and chemotherapy without surgery in these patients.

METHODS

This is a real-world retrospective study. Consecutive patients with stage IVA TM with pleural dissemination who received chemotherapy or upfront surgery between 2007 and 2018 were enrolled. Propensity-score matching (PSM) was used to balance selection bias between groups. Objective response rate (ORR) in pleural lesions to chemotherapy and long-term outcomes including disease-control time (DCT), progression-free survival (PFS) and overall survival (OS) were assessed between groups.

RESULTS

Altogether 168 patients with stage IVA TM with pleural dissemination were enrolled. In 124 patients who received chemotherapy as the first-line treatment, ORR was only 6.5% with no complete remission observed, with 7.3% progression diseases. After PSM, surgery was associated with better prognosis than no-surgery [median DCT: 39.0 vs. 23.0 months, P<0.001; PFS, hazard ratio (HR): 0.457, 95% confidence interval (CI): 0.298-0.700, P<0.001; OS, HR: 0.402, 95% CI: 0.178-0.906, P=0.03]. Significantly more patients received surgery in the later [2016-2018] than in the earlier [2007-2015] time of the study period (72.9% vs. 44.4%, P<0.001), while Bayesian analysis indicated a probability of 94.23% that this shift in treatment was associated with improved PFS.

CONCLUSIONS

Chemotherapy as the first-line treatment is far from satisfactory for stage IVA TMs with pleural dissemination and may not be appropriate as a routine recommendation. Surgery plays a more important role as an alternative option.