I would recommend making sure that the pathology is seminoma (with either review of the orchiectomy specimen and making sure there are trophoblastic elements or a biopsy of the retroperitoneal lymph node) as the beta hCG level is getting close to the upper end of what I would expect from a seminoma....

Mild elevation of HCG can happen from benign trophoblastic elements and would reduce after orchiectomy. Assessing pathology to look for the benign elements will also help in confirming. If the above is confirmed then would treat like seminoma and the option could be RT alone or like recent SAKK da...