AB023. The new TNM classification and Masaoka staging system prognosis of thymoma: a retrospective single-center study
Abstract

AB023. The new TNM classification and Masaoka staging system prognosis of thymoma: a retrospective single-center study

Takao Shigenobu, Takahiro Suzuki, Akira Yoshizu

Department of Thoracic Surgery, Yokohama Municipal Citizen’s Hospital, Kanagawa, Japan

Correspondence to: Takao Shigenobu, MD. Department of Thoracic Surgery, Yokohama Municipal Citizen’s Hospital, 1-1, Mitsuzawanishimachi, Kanagawa-ku, Yokohama City, Kanagawa Prefecture 221-0855, Japan. Email: ta00-shigenobu@hosp.city.yokohama.lg.jp.

Background: The tumor-node-metastasis (TNM) classification of thymic epithelial tumors is based on the eighth edition of the TNM classification. The ninth edition of the TNM classification proposes that the T1 category should be divided by tumor diameter, and the T2 category should include lung and phrenic nerve invasion. The purpose of this study is to reclassify the pathological stage of thymoma based on the proposed TNM classification of the ninth edition and to examine the prognosis.

Methods: Clinicopathological data of the patients who had undergone complete resection for thymoma at Yokohama Municipal Citizens’ Hospital between January 2008 and December 2020 were retrospectively reviewed, and recurrence-free survival (RFS) was evaluated. The T component of the ninth edition of the TNM classification was reclassified as follows: T1a as a tumor diameter of 5 cm or less, T1b as a tumor diameter larger than 5 cm, and T2 as the pericardium, the lung, or the phrenic nerve involvement.

Results: There were 76 cases of completely resected thymoma. The median observation period was 62.1 months (range, 1.9–159.0 months). There were no cases of lymph node metastasis. World Health Organization (WHO) histological classification was A/AB/B1/B2/B3 in 10/33/16/13/4 cases. Recurrence was observed in 6 cases, but no recurrence was observed in T2 or Masaoka stage III cases. According to the ninth edition of TNM classification, T1a/T1b/T2 were 43/30/3 cases, and the 5-year RFS rates of T1a and T1b were 94.6% and 88.2%, respectively. The Masaoka stage I/II/III were 48/25/3 cases, and the 5-year RFS rates of stage I and II were 94.9% and 86.4%, respectively. There were six deaths, but only one death due to thymoma, a T1a, Masaoka stage I, WHO type B3 case.

Conclusions: Thymoma has a good prognosis, but the stage and histological type play important roles in the prognosis, making it difficult to establish an appropriate staging system. A staging system based on accumulating cases at multiple institutions is necessary.

Keywords: Prognosis; staging; thymoma; tumor-node-metastasis classification (TNM classification)

Acknowledgments

Funding: None.

Footnote

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-24-ab023/coif). The 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 (as revised in 2013). The study was approved by the Institutional Review Board of Yokohama Municipal Citizen’s Hospital (No. Z241001) and individual consent for this retrospective analysis was waived.

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-24-ab023
Cite this abstract as: Shigenobu T, Suzuki T, Yoshizu A. AB023. The new TNM classification and Masaoka staging system prognosis of thymoma: a retrospective single-center study. Mediastinum 2024;8:AB023.

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