You can also biopsy one of the metastases rather than the prostate itself -- that's what they did for me (the lesion was on my spine, and they didn't know the origin). There's no need to determine a Gleason score when it's already metastasised, since it's an 8 or 9 pretty-much by definition, and a needle biopsy elsewhere -- if one of the tumours is large enough and accessible -- can confirm prostatic origin without the extra risks and discomfort associated with a prostate biopsy.