This is a multicentre non-randomized phase II study of proton beam radiotherapy in patients with thymic epithelial tumours (i.e. thymoma and thymic carcinoma) in the post-operative setting or in inoperable patients with localized disease.

Patients not willing or for any reason unsuitable to undergo proton treatment will be asked to participate in a follow-up assessment after the regular photon treatment in the same manner as the included patients.

Primary endpoints are:Toxicity (e.g. cardiac and pulmonary toxicity) and Local control at 5 year Secondary endpoints: PFS, Overall survival, Quality of life, measured by EORTC QLQ 30 + LC 13 and relapse pattern

All doses are recorded in Gy(RBE).

After having checked all eligibility criteria patients will receive:

• Patients with radical surgery and unfavourable histology (B2, B3, C) and/or Masaoka-Koga stage III, IVa: 2 Gy(RBE), once daily, five days a week to a total dose of 50 Gy(RBE).
• Patients with non-radical surgery (R1 resection) regardless of stage and histology: 2.3 Gy(RBE), once daily, 5 days a week to a total dose of 57.5 Gy(RBE)
• Inoperable patients regardless of stage and histology and patients with R2 non-radical resection: 2.5 Gy (RBE), once daily, 5 days a week to a total dose of 62.5 Gy(RBE)
• Patients not willing to participate in study will receive photon therapy according to local practice (≥45 Gy)

Induction or adjuvant chemotherapy may be used according to local practice. Concomitant chemotherapy is not allowed.

Inclusion Criteria:

• Histological or cytological diagnosis of thymoma or thymic carcinoma.
• With radical surgery: stage III and IVa and selected stage II with type B2, B3 and thymic carcinoma according to local routine. With non-radical surgery (R1 or R2) or inoperable patient/ patient refusing surgery: stage I - IVa, any histology
• PS WHO 0 - 2.
• FEV1 > 1L or >40 % of predicted and CO diffusion capacity > 40% of predicted (postoperative measures)
• Age >18 years, no upper age limit.
• Written informed consent from patients.

Exclusion Criteria:

• Masaoka-Koga stage IVb (distant metastases).
• Pregnancy.
• Serious concomitant systemic disorder incompatible with the study.
• Tumour motion > 0.5 cm on two repeated 4DCT

The aim is that the study will be published in international journals. A separate publication will include result of the cardiological data The Vancouver declaration (Br Med J:296, 401-405, 1988) should be followed in all publications based on this study.