Growth Kinetics and Short-Term Outcomes of cT1b and cT2 Renal Masses under Active Surveillance

Abstract

Objectives Compared to T1a lesions, the natural history of untreated renal masses is >4cm is poorly understood. We sought to assess the growth kinetics and outcomes of cT1b/T2 cortical renal tumors managed with an initial period of active surveillance (AS), and compared these patients to those who underwent definitive delayed intervention. Methods Our institutional, prospectively maintained, renal tumor database was reviewed to identify enhancing solid & cystic masses managed expectantly. 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. Results 72 tumors >4cm in diameter (in 68 patients) were identified. 45 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 cause and no patient progressed to metastatic disease. Conclusions 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. 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.

Evolving Clinical Picture of Renal Cell Carcinoma: A Population-Based Study from Helsinki

“…Those fit for surgery but not receiving active urological treatment within 6 months of the diagnosis for any reason were included in the AS group. These rules are in line with some other reports [8].…”

“…"Active urological treatment" refers to surgical excision of the tumor by radical nephrectomy or partial nephrectomy, or to the use of percutaneous ablation. Observation indicates that no active urological treatment was delivered within 6 months of diagnosis, as in a previous study [8], and observation was categorized as follows: (1) AS, indicating that the patient with localized sRCC was initially followed by observing his/her condition and tumor characteristics, (2) the patient refused active urological treatment, (3) the patient was unfit for treatment, because any active treatment was considered too risky or not helpful because of limited life expectancy.…”

Addressing metabolic heterogeneity in clear cell renal cell carcinoma with quantitative Dixon MRI

“…The ability to noninvasively detect a metabolic signature associated to grade-4 tumors could be also of value in active surveillance protocols where loss of intratumoral accumulation of fat (i.e., initially detected on a lower-grade tumor) would be indicative of a possible transformation of the tumor toward a more aggressive phenotype. This could be particularly useful in the implementation of active surveillance protocols for larger, heterogenous tumors (e.g., cT1b disease, >4 cm in size), which has been proposed as a reasonable option in select patients with significant comorbidities (50). Moreover, given the intratumoral heterogeneity of FF measures, a better tumor characterization may be achieved by directing percutaneous biopsies toward specific areas of the tumor with lower FF or those where a decrease in FF is documented over time.…”

Cell cycle progression score predicts metastatic progression of clear cell renal cell carcinoma after resection

“…The current CCP score may also have the potential to be a future useful biomarker for patients considering active surveillance, which is now considered even in select patients with clinical T1b and clinical T2 tumors [18,19]. While tumor size, histology, grade and growth kinetics have been the key features used to best predict risk for metastasis of patients on active surveillance, there remains some concern regarding intraobserver and interobserver reproducibility.…”