# Neoadjuvant Concurrent Chemoradiotherapy Versus Neoadjuvant Chemotherapy in Thymic Epithelial Tumors: A Propensity Score-Matched Analysis

## TL;DR

This study compares two pre-surgery treatments for thymic tumors and finds that adding radiation improves resection rates but not survival.

## Contribution

First direct comparison of neoadjuvant chemoradiotherapy and chemotherapy in thymic epithelial tumors using propensity score matching.

## Key findings

- NCRT led to higher complete resection rates and better tumor regression grades compared to NCT.
- No significant difference in overall or recurrence-free survival was observed between the two treatments.
- Treatment failure was mainly due to distant or regional recurrence, not local recurrence.

## Abstract

Thymic epithelial tumors (TETs) are rare malignancies, and evidence guiding the optimal neoadjuvant treatment strategy remains limited. Neoadjuvant chemotherapy (NCT) is commonly used for locally advanced, potentially resectable TETs, while neoadjuvant chemoradiotherapy (NCRT) has been proposed to improve local control. This study is the first to directly compare NCRT and NCT in patients with thymic tumors. Using a retrospective propensity score-matched design, we evaluated surgical and oncologic outcomes between the two strategies. NCRT was associated with significantly higher complete (R0) resection rates and better tumor regression grades, indicating improved local control. However, these advantages did not translate into improved overall or recurrence-free survival. Treatment failure was predominantly driven by regional or distant recurrence rather than local recurrence. These findings suggest that although NCRT may enhance resectability, improving local control alone may be insufficient to improve long-term survival, highlighting the need for more effective systemic treatment strategies in advanced TETs.

Background: Neoadjuvant chemotherapy is generally recommended for locally advanced, potentially resectable thymic epithelial tumors. However, neoadjuvant chemoradiotherapy has been proposed as an alternative approach, potentially achieving higher complete resection rates. In this study, a retrospective analysis was conducted to compare the outcomes of neoadjuvant chemoradiotherapy (NCRT) and neoadjuvant chemotherapy (NCT). Methods: From 2009 to 2022, a total of 98 patients who underwent surgery following either NCRT (n = 30) or NCT (n = 68) for thymic epithelial tumors were included in this study. Propensity score matching was applied, resulting in two matched groups of 30 patients each. The primary endpoint was the comparison of complete (R0) resection rates between the groups. Results: In the matched cohort, the R0 resection rate was significantly higher in the NCRT group (93.3%) compared to the NCT group (73.3%; p = 0.038). The tumor regression grade was also significantly lower in the NCRT group (p = 0.002). However, no significant difference was observed in 5-year overall survival between the groups, either in patients with thymoma (100% for NCRT vs. 90.9% for NCT; p = 0.34) or thymic carcinoma (74.3% for NCRT vs. 63.2% for NCT; p = 0.82). For patients with initial local recurrence, both the 5-year overall survival and post-recurrence survival rates were 100%. Conclusions: The neoadjuvant chemoradiotherapy group demonstrated superior local control, as evidenced by improved tumor regression grades and complete resection rates. However, the absence of corresponding improvement in overall survival warrants further investigation with a larger patient cohort and a longer follow-up period.