Risk of local progression during active surveillance for renal masses under 4 cm
Ryan McLarty1, Rodney H. Breau1,2, Ranjeeta Mallick2, Antonio Finelli3, Simon Tanguay4, Anil Kapoor5, Frédéric Pouliot6, Ricardo A. Rendon7, Bimal Bhindi8, Alan I. So9, Naveen Basappa10, Lucas Dean11, Luke T. Lavallée1,2.
1Division of Urology, Department of Surgery, University of Ottawa, Ottawa, ON, Canada; 2Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada; 3Division of Urology, Department of Surgical Oncology, Princess Margaret Hospital, Toronto, ON, Canada; 4Department of Urology, McGill University Health Centre, Montreal, QC, Canada; 5St. Joseph's Healthcare, McMaster University, Hamilton, ON, Canada; 6Division of Urology, Université Laval, Quebec City, QC, Canada; 7Queen Elizabeth II Health Sciences Centre, Dalhousie University, Halifax, NS, Canada; 8Division of Urology, Department of Surgery, University of Calgary, Calgary, AB, Canada; 9Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada; 10Cross Cancer Institute, University of Alberta, Edmonton, AB, Canada; 11Division of Urology, Department of Surgery, University of Alberta, Edmonton, AB, Canada
Introduction: Active surveillance (AS) is a first-line management option for patients with a small renal mass <4 cm (SRM). Local progression of a SRM during AS may prompt intervention for some patients. There are limited data regarding the long-term risk of progression for patients with a SRM. The objective of this study was to determine the risk of local progression for patients with a SRM on AS.
Methods: Patients enrolled in the Canadian Kidney Cancer information system (CKCis) from January 2011 until October 2021 with a SRM initiating AS were included. Patients were excluded if they had a family history of kidney cancer, multifocal or bilateral tumors, or had metastases at diagnosis. Local progression was defined as a mass growing to >4 cm in diameter (size progression) or a linear growth of >0.5 cm per year (growth progression).
Results: A total of 1173 patients with a SRM met eligibility criteria; 59.5% were male and the mean age was 68.2 years. At diagnosis, 999 (85.2%) of tumors were <3 cm, 646 (55.1 %) were <2 cm, and 145 (12.4%) were <1 cm. At a median followup of six years, 166 patients (14.2%) had size progression and 449 patients (38.3%) had growth progression. In total, 486 (41.4%) of patients experienced any progression event. Five-year freedom from any local progression event was 54%.
Conclusions: This is the largest study to describe the risk of local progression for Canadian patients undergoing AS. Approximately 40% of patients will experience a local progression event within six years of initiating AS. The risk of progression by size and growth definitions varies based on the original tumor size and time on AS. These data will help inform counselling and followup strategies for patients with SRMs <4cm on AS. The prognostic impact of a local progression event on metastases and survival remains to be determined.
