AB036. Trends in thymic epithelial tumor patients in the Netherlands: a population-based study
Original Research

AB036. Trends in thymic epithelial tumor patients in the Netherlands: a population-based study

Marlou Dimmers1, Florit Marcuse2, Lex A. P. W. M. Maat3, Jos G. Maessen4, Jamie L. R. Romeo4, Monique M. H. Hochstenbag2, Stephanie T. H. Peeters5, Ties A. Mulders6, Jan H. von der Thüsen7, Sabrina Siregar3, Daphne W. Dumoulin1

1Department of Pulmonary Medicine, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, the Netherlands; 2Department of Pulmonology, Maastricht University Medical Center, Maastricht, the Netherlands; 3Department of Cardio-Thoracic Surgery, Erasmus MC, Rotterdam, the Netherlands; 4Department of Cardiothoracic Surgery, Maastricht University Medical Center, Maastricht, the Netherlands; 5Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center, Maastricht, the Netherlands; 6Department of Radiology and Nuclear Medicine, Erasmus Medical Center, University Medical Center, Rotterdam, the Netherlands; 7Department of Pathology, Erasmus Medical Center, University Medical Center, Rotterdam, the Netherlands

Correspondence to: Marlou Dimmers, MD. Department of Pulmonary Medicine, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, dr. molewaterplein 40, Rotterdam, 3015GD, the Netherlands. Email: m.dimmers@erasmusmc.nl.

Background: Thymic epithelial tumors (TETs) are rare tumors and the provided care is not standardized. This study describes the population of TET patients in the Netherlands, diagnosed between 2017 and 2023, registered by the Dutch Cancer Registry (NKR). The aim of this study was to analyze changing care patterns for TET patients and differences between high- and low-volume centers regarding surgery and outcome.

Methods: All patients with a new diagnosis of TET between 2017 and 2023 were selected from the NKR database. Data on patient characteristics, staging, treatment and survival were collected and analyzed. Chi-squared test and log-rank test was used to determine differences between high- and low-volume centers. High-volume center was defined as >10 TET surgeries a year.

Results: In total, 965 patients were included. The crude incidence rate of TETs was 7.3/1,000,000. This was 6.1/1,000,000 for thymoma and 1.2/1,000,000 for thymic carcinoma. The mean age was 62.1 years with SD 13.2 and the male:female ratio was 1.15. Surgery was performed in 721 (74.7%) patients, 154 (16%) patients had radiotherapy and 163 (16.9%) patients had chemotherapy. The most commonly used chemotherapy regimen consisted of doxorubicin with cyclophosphamide and cisplatin. In 90 patients no treatment was given for various reasons. Surgery was performed in 25 centers throughout the Netherlands; two were high-volume centers. The number of incomplete resections (R1 and R2) was significantly lower in high-volume centers (9.8%) than in low-volume centers (17.4%) (P=0.02) (Table 1). Survival was significantly higher when resection was complete (P=0.01). Median survival was not reached, 5-year survival was 89% in R0, 82% in R1 and 73% in R2 resections.

Conclusions: This study describes the population of TET patients in the Netherlands and changing care patterns. The number of incomplete resections was significantly lower in high-volume hospitals compared to low-volume. Moreover, complete resection was associated with improved survival. Therefore, centralization of TET care is recommended.

Keywords: Thymic epithelial tumor (TET); thymoma; epidemiology

Table 1

Patient characteristics and outcome high- vs. low-volume centers

Variables Total (n=965) Surgical patients High- vs. low-volume (P)
High-volume centers [n=257 (35.7%)] Low-volume centers [n=462 (64.3%)]
Patient characteristics
   Mean age (years) (SD) 62±13.2
   Gender (M/F) 513/452
TNM
   1 616 (63.8) 199 (77.4) 366 (79.2)
   2 41 (4.2) 10 (3.8) 25 (5.4)
   3a 77 (8.0) 22 (8.6) 30 (6.5)
   3b 18 (1.9) 5 (1.9) 4 (0.9)
   4a 88 (9.1) 16 (6.2) 25 (5.4)
   4b 96 (9.9) 4(1.6) 6 (1.3)
   Unknown 29 (3.0) 1(0.0) 6 (1.3)
Resection outcome
   R0 555 (77.2) 222 (86.4) 323 (69.9) <0.01
   R1 78(10.8) 20 (7.8) 58 (12.6) <0.01
   R2 15 (2.1) 5 (1.9) 10 (2.2) 0.2
   Unknown 81 (11.3) 10 (3.9) 71 (15.4)

Data are presented as mean ± standard deviation or n (%). F, female; M, male; TNM, tumor-node-metastasis.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-25-ab036/coif). J.H.v.d.T. serves as an unpaid editorial board member of Mediastinum from May 2024 to December 2025. S.T.H.P. reports support from Hanarth fund. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics board of the Netherlands Comprehensive Cancer Organization (IKNL) (No. 24-00396). Because this is a database study with anonymous non-traceable data, individual consent was not indicated.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/med-25-ab036
Cite this abstract as: Dimmers M, Marcuse F, Maat LAPWM, Maessen JG, Romeo JLR, Hochstenbag MMH, Peeters STH, Mulders TA, von der Thüsen JH, Siregar S, Dumoulin DW. AB036. Trends in thymic epithelial tumor patients in the Netherlands: a population-based study. Mediastinum 2025;9:AB036.

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