Growth Kinetics of Renal Masses: Analysis of a Prospective Cohort of Patients Undergoing Active Surveillance

• Published in: European urology 2011-05, Vol.59 (5), p.863-867
• Main Authors: Mason, Ross J, Abdolell, Mohamed, Trottier, Greg, Pringle, Christopher, Lawen, Joseph G, Bell, David G, Jewett, Michael A.S, Klotz, Laurence, Rendon, Ricardo A
• Format: Article
• Language: English
• Subjects: Active surveillance; Aged; Aged, 80 and over; Biopsy; Canada; Carcinoma, Renal Cell - diagnostic imaging; Carcinoma, Renal Cell - pathology; Carcinoma, Renal Cell - secondary; Carcinoma, Renal Cell - surgery; Cell Proliferation; Disease Progression; Female; Growth rate; Humans; Kidney Neoplasms - diagnostic imaging; Kidney Neoplasms - pathology; Kidney Neoplasms - surgery; Kinetics; Male; Nephrectomy; Prognosis; Prospective Studies; Radiography; Regression Analysis; Renal cell carcinoma; Renal mass; Risk Assessment; Risk Factors; Tumor Burden; Urology; Watchful Waiting
• ISSN: 0302-2838; 1873-7560
• DOI: 10.1016/j.eururo.2011.02.023

Abstract Background Active surveillance (AS) represents a treatment option for renal masses in patients who are not surgical candidates either because of existing comorbidities or patient choice. Among renal masses undergoing AS, some grow rapidly and require treatment or progress to metastatic disease. Patient and tumour characteristics related to this more aggressive behaviour have been poorly studied. Objective To report the analysis of a multi-institutional cohort of patients undergoing AS for small renal masses. Design, setting, and participants This prospective study included 82 patients with 84 renal masses who underwent AS in three Canadian institutions between July 2001 and June 2009. Intervention All patients underwent AS for renal masses presumed to be renal cell carcinoma (RCC) as based on diagnostic imaging. Measurements Age, sex, symptoms at presentation, maximum diameter at diagnosis (cm), tumour location (central/peripheral), degree of endophytic component (1–100%), and tumour consistency (solid/cystic) were used to develop a predictive model of the tumour growth rate using binary recursive partitioning analysis with a repeated measures outcome. Results and limitations With a median follow-up of 36 mo (range: 6–96), the mean annual renal mass growth rate for the entire cohort was 0.25 cm/yr (standard deviation [SD]: 0.49 cm/yr). Only one patient (1.2%) developed metastatic RCC. Amongst all variables, maximum diameter at diagnosis was the only predictor of tumour growth rate, and two distinct growth rates were identified. Masses that are ≥2.45 cm in largest diameter at diagnosis grow faster than smaller masses. This series was limited by its moderate sample size, although it is the largest published prospective series to date. Conclusions We confirm that most renal masses grow slowly and carry a low metastatic potential. Tumour size is a predictor of tumour growth rate, with renal masses 2.45 cm.