#AUA14 - Session Highlights: Experience with active surveillance (AS) in patients with renal mass ≥ 4cm: Assessment of growth kinetics and outcomes

ORLANDO, FL USA (UroToday.com) - Although level I evidence supporting active surveillance (AS) of solid malignancies is absent, institutional studies and pooled analyses provide robust contemporary data that an initial short-term period of observation to determine tumor growth kinetics may be safe for small enhancing tumors, in select candidates. Compared to T1a lesions, the natural history of untreated renal masses is > 4cm is poorly understood. Authors sought to assess the growth kinetics and outcomes of cT1b/T2 cortical renal tumors managed with an initial period of active AS, and compared these patients to those who underwent definitive delayed intervention.

auaAn institutional, prospectively maintained renal tumor database at Fox Chase Cancer Center was reviewed to identify enhancing solid and cystic masses managed expectantly from 2000−2012. Clinically localized tumors > 4.0 cm (≥ T1b) that were radiographically followed for > 6 months were included for analysis. Tumor size at presentation, annual linear tumor growth rate (LGR), Charlson comorbidity index (CCI), length of follow−up (FU), and clinical outcomes were compared between those who remained on AS or those who underwent delayed surgical intervention using ANOVA and Chi square tests. Adjusting for patient and tumor characteristics, logistic regressions were used to test for associations with progression to definitive surgical intervention.

After all the exclusions, a total of 72 tumors ≥ 4cm in diameter (in 68 patients) were identified. Forty-five patients (66%) were managed solely with AS, while 23 (34%) progressed to intervention. For all lesions, the median tumor size at presentation was 4.9 cm, and the mean LGR was 0.44 cm/year. 14.7% of masses demonstrated no growth over time. Comparing patients managed exclusively with AS and those progressing to definitive intervention, no differences were noted in median tumor size at presentation (4.9 vs 4.6 cm, p=0.79) or median CCI (3 vs 2, p=0.6), while significant differences were seen with respect to median age at presentation (77 vs 60 years, p=0.0002) and mean LGR (0.37 vs 0.73 cm/year, p=0.02). Following adjustment, younger patients (OR 0.91 [CI 0.86-0.97]) and tumors with faster LGR (OR 9.1 [CI 1.7-47.8]) were more likely to undergo delayed surgical intervention. With a median FU of 32 months (mean, 38.9 ± 24.0; range 6−105), 9 patients died (13%) from other causes and no patient progressed to metastatic disease. Reported findings from this abstract indicate that localized cT1b or larger renal masses show comparable growth rates to small tumors managed expectantly with low rates of progression to metastatic disease at short term follow up. Also, perhaps an initial period of AS to determine tumor growth kinetics is a reasonable option in select patients with significant competing risks and limited life expectancy.

Presented by Reza Mehrazin, MD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA

Fox Chase Cancer Center, Philadelphia, PA USA

Written by Reza Mehrazin, MD, medical writer for UroToday.com