When will you consider doing a biopsy of a potential metastatic site (lymph node, lung/visceral) for testicular cancer after orchiectomy?

I will biopsy a potential metastatic deposit seen on the scan after the orchiectomy if tumor markers are negative, have reduced to normal with appropriate half-lives, or are equivocal. A raised LDH, in isolation, is not enough to support the diagnosis of metastasis, and I will usually biopsy if that is the only raised marker. A very high level of HCG (above 500-1000 IU/ml) is strongly suggestive of the presence of elements of choriocarcinoma, although I have certainly seen metastatic, biopsy-proven pure seminoma with a level of HCG of 500 and a negative AFP. Persistently elevated AFP, if one has excluded hepatic origin, etc., indicates the presence of NSGCT. Follow-up of tumor markers and CT scan appearance after initiation of treatment is ...