Generally, not before the PSA reaches 50 ng/ml; however, some high grade tumors that do not produce much PSA might produce metastases at lower PSA levels. The best way to be sure is to have a bone scan, at least yearly, if the PSA is rising. An abdominal and pelvic CT scan is also helpful to determine whether there are metastases in lymph nodes or other internal organs. The important point is that with intermittent hormonal therapy, if the PSA level is maintained between zero and four, there is a very low likelihood that the cancer will have spread.