62-year-old male with Masaoka stage II thymic carcinoma (disease extension into the mediastinal fat), s/p robotic thymectomy with close surgical margins (<1 mm). He developed paraneoplastic Lambert-Eaton syndrome, which partially resolved after surgery.


He was treated with post-operative EBRT with IMRT (with daily IGRT) to 50 Gy in 25 Fx (2 Gy/Fx) prescribed to the 100% isodose line. A free breathing technique was used in this case.

CT Simulation Scan Details:

  • Position: Head first, supine, arms up, legs straight, head/chin neutral 
  • Immobilization: Wingboard
  • Respiratory motion: Strongly consider DIBH, 4D-CT for respiratory motion management.
  • Scan range: from neck to mid-abdomen, could consider using IV contrast (not utilized in this case)


  • Fuse pre-surgical imaging with planning CT scan to facilitate target delineation. Match to mediastinal anatomy, not spinal anatomy.

  • Contour pre-operative GTV to guide CTV extent.

  • Any residual visible tumor after surgery should be contoured as GTV. Thoracic surgeons may place surgical clips to indicate areas of concern. In this case, there was no residual GTV.

  • CTV should include: residual gross (GTV) or microscopic disease based on pre-operative imaging, operative findings, and pathological examination. This typically includes the original extent of disease adjusted to account for anatomical changes after surgery and organs not at risk of involvement (e.g., lung that was displaced by a mediastinal mass), as well as surgical clips indicating regions at particular risk for persistent microscopic disease.

  • Elective nodal irradiation is not indicated.

  • PTV should consider potential target motion and daily setup variation. Target motion is generally small in the post-operative setting. Expansions for daily setup variation can be minimized by using daily IGRT.



  • There are no randomized studies evaluating post-operative radiation treatment (PORT) in thymic carcinoma. Most evidence is based on retrospective data (Kondo K et al. 2003,Omasa et al. 2015,Tateishi et al. 2021).

  • Compared to thymomas, thymic carcinomas have a higher risk of recurrence.

  • PORT is recommended for stage II-III resected thymic carcinomas. Margins are inevitably close or positive, given anatomical limitations. Dosing is recommended as follows:

Post-Op (Thymic carcinoma)

Post-Op RT Dosing (1.8-2 Gy per fraction)

R0 (negative margins)

45-50 Gy

R1 (microscopic disease)

54 Gy

R2 (gross residual)

60 Gy

  • Patients with unresectable disease: ~60 Gy with concurrent chemotherapy could be considered.

  • If surgical margins are positive, chemotherapy may also be considered.

  • Lambert-Eaton Syndrome is frequently associated with SCLC but can be associated with other cancers, including thymic malignancies (10-15%) Morimoto et al. 2010.