Narrative review: locally advanced thymoma-do we really need induction therapy before extended resection?

Locally advanced thymoma remains a challenging condition in which complete tumour clearance may require extended surgical resection. Induction therapy, including chemotherapy or chemoradiotherapy, is used in selected patients to improve resectability; however, the evidence supporting its routine use remains limited. This narrative review evaluates the role of induction therapy before extended resection, with particular attention to patient selection, resectability assessment, and multidisciplinary decision-making.

A structured narrative review was conducted using PubMed/MEDLINE, supplemented by manual screening of reference lists from relevant articles, reviews, registry analyses, and guideline documents. The original search covered the period from January 1990 to April 2026 and was updated on 21 June 2026 during revision. Search terms included combinations of "thymoma", "thymic epithelial tumours", "locally advanced", "induction therapy", "neoadjuvant treatment", "preoperative chemotherapy", "chemoradiotherapy", "resectability", "borderline resectable", and "extended resection". English-language clinical studies, systematic and narrative reviews, registry analyses, and international guidelines were considered.

The available evidence is largely derived from retrospective, heterogeneous studies, often including mixed populations of thymoma and thymic carcinoma. Platinum-based regimens can achieve radiologic response rates of approximately 50-70%, but no prospective or randomised data demonstrate a clear survival advantage over upfront surgery in clearly resectable thymoma. Induction therapy may provide practical advantages in selected anatomically complex or borderline-resectable cases, including tumour bulk reduction, improved operative planning, and potential facilitation of margin-negative resection. However, radiologic response does not necessarily indicate true pathologic downstaging or reduced need for en bloc resection. Current evidence therefore supports a selective, rather than routine, use of induction therapy following multidisciplinary assessment.

Extended surgical resection remains the standard of care when complete resection appears achievable upfront. Current evidence is insufficient to support routine induction therapy in clearly resectable locally advanced thymoma, although induction treatment remains appropriate in selected borderline-resectable cases in which preoperative therapy may improve the likelihood or quality of complete resection. Further prospective and collaborative studies are needed to refine patient selection and clarify its role.