A matched analysis of active surveillance vs. nephrectomy for small renal masses
Douglas Cheung1, Lisa J. Martin1, Maria Komisarenko1, Kristen McAlpine1, Shabbir M. Alibhai2, Antonio Finelli1.
1Department of Surgery, Division of Urology, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; 2Department of Medicine, University Health Network, Toronto, ON, Canada
Introduction: While studies have shown that patients with a small renal mass (SRM) managed on active surveillance (AS) maintain excellent metastasis-free (MFS) and cancer-specific survival (CSS), observed differences in overall survival (OS) may be explained by older/more comorbid patients selecting AS. Few studies have evaluated the outcomes of AS vs. primary intervention in clinically-balanced patient groups.
Methods: Patients with a SRM (≤4 cm T1a) aged 55–75 were identified from our institutional database (2000–2020). Those with a prior cancer history/family history or undergoing radiofrequency ablation were excluded. Demographic and clinical information were extracted to assess OS and a composite event-free survival (EFS) outcome, which included OS, CSS, MFS, progression, or systemic therapy, using Cox proportional hazards models. To better adjust for clinical characteristics, patients receiving AS versus nephrectomy were exact-matched on age, sex, Eastern Cooperative Oncology Group (ECOG) score, biopsy status, and histology.
Results: We identified 377 SRM patients, of which 205 were managed by AS and 172 by nephrectomy. The cohort was balanced after matching (n=110) (Table 1): age 64 years, 77% male, and 75% ECOG 0. In each arm, 47% of patients had a biopsy, with predominantly clear-cell histology. In the matched cohort, the predicted five-year OS was 95.7% for nephrectomy and 94.8% for AS (p=0.84; hazard ratio [HR] nephrectomy vs. AS 0.83, 0.13–5.32), while the EFS was 92.7% and 96.0%, respectively (p=0.47; HR nephrectomy vs. AS 1.88, 0.35–10.15).
Conclusions: In SRM patients well-matched for age and comorbidity, we observed much higher five-year OS and EFS rates for AS than those previously reported, with point estimates that were comparable to nephrectomy. Furthermore, our matched characteristics approximate the treatment arms of contemporary cohorts (i.e., the patient population equally eligible for AS or primary intervention), suggesting that AS is a safe management strategy in younger, healthier patients.
