In a phase II trial reported in The Lancet Oncology, Brian I. Rini, MD, of the Cleveland Clinic Taussig Cancer Institute, and colleagues found that some patients with metastatic renal cell carcinoma can safely undergo active surveillance for an extended duration prior to initiation of systemic therapy. Indolent growth of metastases is known to occur in some patients with metastatic renal cell carcinoma.
In the study, 52 patients with treatment-naive asymptomatic metastatic renal cell carcinoma were enrolled from 5 sites in the United States, Spain, and the United Kingdom. Patients were radiographically assessed at baseline, every 3 months during year 1, every 4 months during year 2, and every 6 months thereafter. Patients were observed until systemic therapy was started, based on the decision of the treating physician and patient. The primary endpoint was time to initiation of systemic therapy in the per-protocol population. Follow-up is ongoing.
Median follow-up was 38.1 months. Among 48 patients included in the per-protocol analysis, median duration of surveillance until the start of systemic therapy was 14.9 months. Response Evaluation Criteria in Solid Tumors (RECIST)-defined disease progression occurred in 43 patients (90%), with 37 starting therapy. Median time to disease progression was 9.4 months; 23 patients (53%) with disease progression started systemic therapy immediately after disease progression. The median additional surveillance duration among the 20 patients not immediately starting therapy after disease progression was 15.8 months.
On multivariate analysis, a greater number of International Metastatic Database Consortium (IMDC) adverse risk factors (P = .0403) and a greater number of metastatic sites (P = .0414) were associated with a shorter surveillance period. In a favorable-prognosis group consisting of 29 patients (60%) with ≤ 1 IMDC risk factor and ≤ 2 organs with metastatic disease, estimated median surveillance duration was 22.2 months; in an unfavorable-prognosis group consisting of the remaining 19 patients, estimated median surveillance duration was 8.4 months (P = .0056). Overall, 22 (46%) patients died during the study, all from metastatic renal cell carcinoma.
The investigators concluded: “A subset of patients with metastatic renal-cell carcinoma can safely undergo surveillance before starting systemic therapy. Additional investigation is required to further define the benefits and risks of this approach.”