Active surveillance prior to initiating targeted therapy might benefit some patients with metastatic renal cell carcinoma (mRCC), according to a retrospective study (abstract 435) presented at the 2017 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, held February 16–18 in Orlando, Florida.
“Active surveillance does not affect the efficacy of subsequent therapies,” reported lead study author Davide Bimbatti, MD, of the Azienda Ospedaliera Universitaria Integrata, University of Verona in Verona, Italy. “In selected patients, active surveillance allows us to delay the start of systemic treatment; patients in active surveillance rarely have a worsening of prognostic class.”
Targeted therapies can improve survival among patients with mRCC, but treatment-related adverse events can worsen quality of life and force discontinuation of treatment. Active surveillance delays systemic therapy and toxicities.
To determine how active surveillance affects tumor burden and patient prognosis in patients with indolent disease, the research team conducted a single-institution study to test time on surveillance, overall survival and post-surveillance overall survival, progression-free survival, and tumor burden outcomes among 48 patients with mRCC who underwent active surveillance between 2007 and 2016. Changes in International mRCC Database Consortium (IMDC) prognostic class and tumor burden were analyzed for associations with these outcomes.
The baseline IMDC prognostic class was favorable in 69% of patients, intermediate in 25%, and poor in 6%. At a median follow-up of 37.3 months, 79.2% of patients were still alive.
At a median surveillance duration of 16.7 months, 71% of patients had started a targeted therapy.
Only four patients changed from good to intermediate IMDC prognostic class; overall, IMDC classes “maintained their prognostic value” among patients who underwent active surveillance, Bimbatti said. IMDC class was the “sole factor” that was associated with time on surveillance.
Significant differences in time on surveillance were found for patients with good or intermediate vs poor prognosis (19.9, 17.7, and 5.2 months, respectively; P < .04), Bimbatti reported.
Change in tumor burden was not associated with time on surveillance. It was associated with post-surveillance overall survival (hazard ratio [HR], 1.23; P < .01), but not with overall survival. Higher baseline number of metastatic sites was associated with significantly worse overall survival (HR, 3.3; P < .01). Time on surveillance and overall survival were similar to previous studies.
The decision to end surveillance was “not mandated per objective criteria but left to the physician’s and patient’s discretion,” cautioned Bimbatti.
The findings offer “reassuring data,” said Primo N. Lara, Jr, MD, of the University of California, Davis Comprehensive Cancer Center. “Very few active surveillance patients evolved into a worse prognostic group.”
The study was retrospective and conducted at a single institution, and “failed to account for psychosocial issues like anxiety,” Lara cautioned. “But the bottom line is that active surveillance remains a reasonable option for highly selected patients.”