Inclusion Criteria:  Histological diagnosis of classical seminoma Primary site - testis, mediastinum or retroperitoneum Stage IIB-IIIC (AJCC 8th edition) Age>18 years Karnofsky Performance Status at least 70 A response assessment FDG PETCT scan done at least twelve weeks after the first line chemotherapy, showing a persistent measurable residual mass Patient willing and reliable for follow up and QOL.  Exclusion Criteria:  Histology other than classical seminoma Non completion of planned first-line chemotherapy Prior history of radiotherapy to the involved region Inability to deliver adequate radiotherapy dose safely based on assessment by radiation oncologist