Testicular germ cell tumour arising 15 years after radiotherapy with 18 Gy for germ cell neoplasia in situ.

Purpose: Germ cell neoplasia in situ (GCNis), the precursor of adult testicular germ cell tumours (GCTs), is found in 5-6% of contralateral testicles in patients with testicular GCT and in the tumour-surrounding tissue of > 90% of testes undergoing testis-sparing surgery (TSS) for GCT. Local radiotherapy to the testis with 18-20 Gy eradicates GCNis while preserving Leydig cells. The frequency of treatment failures is so far unknown.