Adverse pathologic characteristics in the small renal mass: implications for active surveillance.

Introduction: Evidence has demonstrated that tumor size is related to adverse oncologic outcomes in small renal tumors (≤ 4 cm). We evaluated the association of adverse pathologic features (APF) with tumor size and survival in patients with a small renal mass (SRM).
Materials and Methods: We retrospectively reviewed the pathologic characteristics of 380 surgically resected SRMs from a single institution. APFs included lymphovascular invasion, coagulative necrosis, sarcomatoid/rhabdoid features, papillary type II histology, and perinephric fat/renal sinus invasion. The number and type of APFs were compared with tumor size. Survival analysis was performed using the Kaplan-Meier method.
Results: There were 244 (64.2%) males and 136 (35.8%) females. The median age was 61 years, and median tumor size was 2.7 cm. The median follow up time was 65 months. A significant association was found between tumor size and presence of APFs (p = 0.018). At least 1 APF could be found in 22%, 32%, 36%, and 49% of tumors ≤ 1 cm, 1 cm-2 cm, 2 cm-3 cm, and 3 cm-4 cm, respectively. There were no differences in overall survival or recurrence free survival when compared by tumor size at diagnosis (p = 0.22 and 0.15 respectively). Compared to patients with ≤ 1 APFs, disease specific survival was worse for patients with ≥ 2 APFs (p < 0.002).
Conclusion: Our data support that aggressive tumor biology in a SRM is associated with greater size. In patients with a SRM, the decision to pursue active surveillance and the trigger for intervention should take tumor size and APFs into consideration as this may have future oncologic implications.