Therapy De-escalation in Seminoma Stage IIA/B

Inclusion Criteria:

* Patient has given written informed consent before registration.
* Histologically confirmed classical seminoma treated with primary inguinal orchidectomy.
* Tumor stage at diagnosis or at relapse after primary active surveillance is pT1-4\* cN1-2 cM0 according to UICC TNM 2009 is pT1-4 cN1-2 cM0 according to UICC TNM 2009.
* Multi-slice CT or MRI or FDG-PET-CT of the chest, abdomen and pelvis or a FDG-PET-CT within 4 weeks prior to patient registration, showing stage IIA/B disease. I.v. contrast medium has to be administered.
* Age ≥ 18 years.
* WHO performance status 0-2.
* Adequate hematological values: neutrophils ≥ 1.0 x 109/L, platelets ≥ 100x 109/L.
* Adequate renal function (calculated creatinine clearance ≥ 50 ml/min, according to the formula of Cockcroft-Gault).
* Patient agrees not to father a child during trial treatment and during 12 months thereafter.
* Patient has been proposed sperm conservation.
* Patient compliance and geographic proximity allow proper staging and follow-up for at least 3 years.

Exclusion Criteria:

* Previous or concurrent malignancy within 5 years with the exception of localized non-melanoma skin cancer or stage I seminoma for patients entering the trial with relapse during active surveillance.
* Psychiatric disorder precluding understanding of information on trial-related topics or giving informed consent or interfering with compliance for treatment schedule.
* Mixed histology seminoma.
* Elevated levels of AFP (≥ULN) at any time.
* Any prior abdominal/pelvic radiotherapy (RT).
* Any anti-cancer therapy after primary tumor resection (active surveillance for stage I disease is not considered as a treatment).
* Any treatment in a clinical trial within 30 days of trial entry.
* Any serious underlying medical condition or serious co-morbidity (at the judgment of the investigator) which could impair the ability of the patient to participate in the trial.
* Any contraindication for the trial drug (for example, known hypersensitivity to trial drug or to any other co-component of the trial drug, past or current renal insufficiency, severe hepatic insufficiency, severe bone marrow dysfunction, tumor bleeding, major hearing defects).
* Any concomitant drugs contraindicated for use with the trial drug according to the approved product information (for example, nephrotoxic or ototoxic medicines).