Effect of delayed resection after initial surveillance and tumor growth rate on final surgical pathology in patients with small renal masses (SRMs)

Objective: To understand potential harms associated with delaying resection of small renal masses (SRMs) in patients ultimately treated, and whether these patients have factors associated with adverse pathology.

Methods: Patients with SRMs (≤4cm) who underwent surgical resection at our institution (2009-2015) were classified as undergoing early resection or initial surveillance with delayed resection (defined by a time from presentation to intervention of at least 6mo). Demographic and clinical variables were compared among groups. Using multivariable logistic regression, we examined the association between delayed resection and adverse pathology (Fuhrman grade 3-4, papillary type 2, sarcomatoid histology, angiomyolipoma with epithelioid features, or stage≥pT3). For patients who underwent delayed intervention, we used similar methods to examine the association between SRM growth rate and adverse pathology.

Results: Overall, 401 (81%) and 94 (19%) patients underwent early and delayed resection, respectively. Median time to resection was 84 days (interquartile range: 59-121) and 386 days (interquartile range: 272-702) (P<0.001). Patients undergoing delayed resection were older (62 vs. 58y, P = 0.01) and had smaller masses (2.3 vs. 2.7cm, P<0.001) at initial presentation. Utilization of partial vs. radical nephrectomy was similar regardless of resection timing (P = 0.5). Delayed resection was not associated with adverse pathology (P = 0.8); however, male sex was independently associated with adverse pathology (odds ratio: 1.7, 95% CI: 1.1-2.4, P = 0.009). In patients on surveillance, increasing annual SRM growth rate was associated with adverse pathology (odds ratio: 1.2, 95% CI: 1.03-1.3mm/y, P = 0.02).

Conclusions: Delayed resection was not associated with adverse pathology. Patients on surveillance with increased SRM growth rates had a modest but significant increase in the risk of adverse pathology.