Small Renal Masses Managed With Active Surveillance: Predictors of Tumor Growth Rate After Long-Term Follow-Up.

Background The purpose of the study was to evaluate the relationships between the patients' clinical characteristics and the growth pattern of SRMs, and to investigate the predictive factors of tumor growth rates in patients initially managed with AS. Materials and Methods We retrospectively reviewed data from our prospectively collected database of 70 patients diagnosed with 72 SRMs between 1996 and 2013. Clinical and demographic data, and linear and volumetric growth rates were recorded for each patient. A Pearson correlation test was used to evaluate initial tumor size and linear or volumetric growth rate. Logistic regression models were used to evaluate the predictive factors affecting tumor growth kinetics. Results The mean age was 76 ± 6.8 years, and 47 (67.1%) of patients were male. The mean (± SD) and the median (interquartile range [IQR]) tumor size at presentation were 2.1 ± 1.3 and 2.7 (1.8-3.7) cm, respectively. The mean (± SD) and the median (IQR) linear growth rate were 0.5 ± 0.3 and 0.6 (0.4-1.5) cm per year, respectively. Patients treated with delayed surgery experienced a significantly greater mean linear growth rate (1.4 vs. 0.3 cm per year) than those observed in the AS group (P <.001). Male sex (HR, 1.70; P =.04) and symptomatic presentation (HR, 1.85; P =.02) were found to be significant predictors of tumor growth rates during AS. Conversely, age, Charlson Comorbidity Index, and initial tumor size failed to predict growth kinetics. Conclusion Male sex and symptomatic presentation are associated with faster growth rates in patients managed with AS after long-term follow-up.