Follow-Up After Treatment

The optimal follow-up strategy for men treated for prostate cancer is uncertain. Men should be interviewed and examined for symptoms or signs of recurrent or progressing disease, as well as side effects of therapy that can be managed by changes in therapy. However, using surrogate end points for clinical decision-making is controversial, and the evidence that changing therapy based on such end points translates into clinical benefit is weak. Often, rates of PSA change are thought to be markers of tumor progression. However, even though a tumor marker or characteristic may be consistently associated with a high risk of prostate cancer progression or death, it may be a poor predictor and of limited utility in making therapeutic decisions.

Although the PSA test is nearly universally used to follow patients, the diversity of recommendations on follow-up care reflects the lack of research evidence on which to base firm conclusions. A systematic review of international guidelines highlights the need for robust primary research to inform future evidence-based models of follow-up care for men with prostate cancer.[53]

Preliminary data from a retrospective cohort of 8,669 patients with clinically localized prostate cancer treated with either radical prostatectomy or radiation therapy suggested that short posttreatment PSA doubling time (<3 months in this study) fulfills some criteria as a surrogate end point for all-cause mortality and prostate cancer-specific mortality after surgery or radiation therapy.[54]

Likewise, a retrospective analysis (SWOG-S9916 [NCT00004001]) showed PSA declines of 20% to 40% (but not 50%) at 3 months and 30% or more at 2 months after initiation of chemotherapy for hormone-independent prostate cancer, and fulfilled several criteria of surrogacy for overall survival (OS).[55]

These observations should be independently confirmed in prospective study designs and may not apply to patients treated with hormonal therapy. In addition, there are no standardized criteria of surrogacy or standardized cut points for adequacy of surrogate end points, even in prospective trials.[56]