When should serum tumor markers be obtained to monitor treatment response?

The most appropriate timing for obtaining serum tumor markers to monitor treatment response is at diagnosis, specifically after orchiectomy. This is crucial because it establishes a baseline level of the tumor marker which can be used for comparative purposes throughout the treatment process. After surgery, this marker level helps gauge how well the treatment is working. Monitoring tumor markers at this stage allows for an accurate assessment of whether disease progression occurs or if the cancer is responding to therapy.

Obtaining tumor markers during surgery does not provide useful information for monitoring treatment response since levels can be affected by the procedure itself. Similarly, collecting them before any intervention would not yield meaningful insights into the effectiveness of treatment either since there would be no treatment to respond to. Lastly, waiting to check tumor markers only after chemotherapy could miss the critical baseline information needed to assess the overall effectiveness of treatment and track changes over time.