Reduced Intensity Radio-chemotherapy for Stage IIA/B Seminoma

Inclusion Criteria: * Written informed consent according to ICH/GCP (International Council on Harmonization/Good Clinical Practice) regulations before registration and prior to any trial specific procedures * Histologically confirmed classical seminoma treated with primary inguinal orchidectomy or partial orchidectomy * Patients with a seminoma stage IIA or IIB, either newly diagnosed or recurrent after primary active surveillance, adjuvant carboplatin or radiotherapy for stage I disease. The tumor stage is pT1-4 cN1-2 cM0 according to UICC TNM 8th edition 2016. Patients with a recurrent seminoma stage IIA or IIB are only eligible in case of progression under active surveillance or recurrence after adjuvant carboplatin or radiotherapy for stage I disease * Stage IIA, in patients with equivocal lymph node enlargement, needs to be confirmed with a repeated CT/MRI scan of the abdomen (suggested timeframe: 4 weeks after the previous scan) in order to rule out false positive lymph node enlargement. Patients with a prior malignancy treated with curative intention are eligible if all treatment of that malignancy was completed at least 5 years before registration and the patient has no evidence of disease at registration. Less than 5 years is acceptable for malignancies with low risk of recurrence and/or no late recurrence. Patients with a germ cell neoplasia in situ (GCNIS) or contralateral localized treated seminoma are eligible * Diagnostic CT or MRI or FDG-PET-CT of the chest,…