Reliability of Serum Tumor Marker Measurement to Diagnose Recurrence in Patients with Clinical Stage I Nonseminomatous Germ Cell Tumors Undergoing Active Surveillance: A Systematic Review

PURPOSE: Men with nonseminomatous germ cell tumors of the testicle without evidence of residual disease after radical orchiectomy (clinical stage I) are increasingly managed with active surveillance. The guideline-recommended cornerstones of surveillance are conventional serum tumor markers and computerized tomography. The reliability of serum tumor markers as a tool to diagnose early recurrence of clinical stage I nonseminomatous germ cell tumors is unclear. The study objective was to conduct a systematic review of the currently available evidence assessing the reliability of serum tumor markers as a test to diagnose recurrence in patients with clinical stage I nonseminomatous germ cell tumors under active surveillance. MATERIALS AND METHODS: A systematic review was conducted in accordance with PRISMA guidelines, with no language or date restrictions. Studies were included that readily identified the tumor marker status of patients with clinical stage I nonseminomatous germ cell tumors who had a recurrence on active surveillance. The primary outcome was marker positivity at the time of recurrence. Risk of bias assessment was undertaken. RESULTS: A total of 2,157 studies were identified and independently screened by 2 reviewers, with 37 studies ultimately being included. A relatively high risk of bias was identified among the studies, with the vast majority being retrospective series. The total population for the included studies was 8,545 patients with clinical stage I nonseminomatous germ cell tumors managed by active surveillance, and 2,254 ultimately relapsed. Serum tumor markers were elevated in 28% to 75% of patients at the time of recurrence and were the only indication of recurrence in 4% to 39%. The unavailability of patient-level data is the major limitation to the present findings. CONCLUSIONS: In patients with clinical stage I nonseminomatous germ cell tumors managed by active surveillance, the use of serum tumor markers cannot obviate the need for computerized tomography. More reliable serum markers are needed in order to limit radiation exposure for these patients.