ORLANDO – Active surveillance prior to initiating targeted therapy could be an option for some patients with metastatic renal cell carcinoma (mRCC), according to new findings.
“Active surveillance does not affect the efficacy of subsequent therapies,” said lead study author Davide Bimbatti, MD, of the Azienda Ospedaliera Universitaria Integrata, University of Verona (Italy). “In selected patients, active surveillance allows us to delay the start of systemic treatment, and patients in active surveillance rarely have a worsening of prognostic class,” he said in a press briefing held at the 2017 Genitourinary Cancers Symposium sponsored by the American Society of Clinical Oncology, ASTRO, and the Society of Urologic Oncology.
Targeted therapies can improve survival in mRCC but treatment is not curative and associated toxicities can interfere with quality of life and force patients to discontinue treatment. Active surveillance delays the use of systemic therapy and associated toxicities, and is a feasible strategy for patients with indolent disease.
However, the effect of active surveillance on tumor burden and prognosis have not been investigated.
To address this issue, Dr. Bimbatti and his colleagues conducted a retrospective study and evaluated the effect of active surveillance on overall survival and postsurveillance overall survival, progression-free survival, and tumor burden (a measure of the number of sites and tumor size).
The study cohort included 48 patients with mRCC who underwent active surveillance during 2007-2016 and changes in the International mRCC Database Consortium (IMDC) prognostic class and tumor burden were analyzed for associations with these endpoints.
At baseline, 69% of patients had a favorable prognostic IMDC class, 25% were at an intermediate class, and 6% had a poor class designation. The main sites of metastases were lung (56%), lymph nodes (25%), pancreas (14%), adrenal gland (8%), CNS (8%), and bone (6%).
At a median follow-up of 37.3 months, 79.2% of patients were still alive and, at a median surveillance duration of 16.7 months, 71% of patients had begun a targeted therapy. There were a total of 17 deaths (33%).
Median progression-free survival was 16.6 months and median postsurveillance overall survival was 39.1 months.
During active surveillance, only four patients transitioned from good to intermediate IMDC prognostic class. IMDC classes overall maintained their prognostic value during active surveillance, Dr. Bimbatti said. IMDC class was also the only factor that was associated with time on surveillance.
At baseline, tumor burden was in one site for 65% of patients, two sites in 31%, and three or more sites for 4%, but during active surveillance, changes occurred in one site in 35% of patients, two in 48%, and more than two in 17%.
A change in tumor burden (greater than or equal to 2.2 times the original burden), however, was related to poorer postsurveillance survival (hazard ratio,1.23; P less than .01), but not with overall survival (HR, 1.0; P less than .05).
Conversely, any increase in metastatic sites was associated with both significantly worse postsurveillance and overall survival (HR = 2.6, P = 0.04; and HR = 3.3, P less than 0.01).
Commenting on the study, Primo N. Lara Jr., MD, of the University of California, Davis, Comprehensive Cancer Center explained that active surveillance “remains a reasonable option for highly selected patients.”
“[The investigators] provide reassuring data that active surveillance does not alter the IMDC risk grouping,” he said, and that the results of this study overall, were similar to those of prior research.
There were some limitations to the study, in that it was retrospective and conducted at a single institution. “It also failed to account for psychosocial issues such as anxiety during the active surveillance phase,” he said.
Critical questions also remain, Dr. Lara added, such as what are the validated selection criteria for patients entering active surveillance or what is the threshold of tumor burden to warrant active surveillance discontinuation.
The funding source was not disclosed. Dr. Bimbatti and his coauthors have no disclosures. Dr. Lara reports financial ties to multiple pharmaceutical companies.