Conditional survival of patients with small renal masses undergoing active surveillance

Firas G Petros; Aradhana M Venkatesan; Diana Kaya; Chaan S Ng; Bryan M Fellman; Jose A Karam; Christopher G Wood; Surena F Matin

doi:10.1111/bju.14486

Conditional survival of patients with small renal masses undergoing active surveillance

BJU Int. 2019 Mar;123(3):447-455. doi: 10.1111/bju.14486. Epub 2018 Aug 27.

Authors

Firas G Petros¹, Aradhana M Venkatesan², Diana Kaya², Chaan S Ng², Bryan M Fellman³, Jose A Karam¹, Christopher G Wood¹, Surena F Matin¹

Affiliations

¹ Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
² Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
³ Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

PMID: 30007044
DOI: 10.1111/bju.14486

Abstract

Objectives: To determine conditional survival for patients with small renal masses (SRMs) undergoing active surveillance (AS).

Materials and methods: Patients were enrolled in a prospective AS protocol at our institution between May 2005 and January 2016. Patients with SRMs ≤4 cm with serial cross-sectional imaging available in-house for review were included. Overall survival (OS) was estimated using the Kaplan-Meier method and modelled via Cox proportional hazards models. The primary endpoints analysed were the conditional probability of survival and tumour growth over time. Landmark analysis was used to evaluate survival outcomes beyond the 2-year mark after the initial scan. The relative conditional survival of patients on AS was compared to those undergoing partial nephrectomy (PN) using inverse probability of treatment weighting.

Results: A total of 272 patients were included in this analysis. The mean initial SRM size was 1.74 ± 0.77 cm, and the mean mass size closest to the 2-year mark was 1.97 ± 0.83 cm. The likelihood of continued survival to 5 years improved after the 2-year landmark. Patients with masses <3 cm who survived the first 2 years on AS had a 0.84-0.85 chance of surviving to 5 years, and if they survived 3 years, the probability of surviving to 5 years improved to 0.91. A slow tumour growth (β: 0.12; P < 0.001) with parallel growth rates was found for tumours <3 cm. Patients on AS and those who underwent PN had similar OS for ~7 years, beyond which PN demonstrated a trend of lower risk of death compared with AS (hazard ratio 0.57; P = 0.07).

Conclusions: The conditional survival probability of patients with SRMs <3 cm on AS increased after 2 years. This information may prove useful to urologists and patients who are considering continuing AS vs intervention after the first 2 years on AS.

Keywords: active surveillance; conditional survival; landmark analysis; renal cell carcinoma; small renal masses.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Carcinoma, Renal Cell / diagnostic imaging
Carcinoma, Renal Cell / mortality*
Carcinoma, Renal Cell / pathology
Carcinoma, Renal Cell / therapy
Female
Humans
Kidney Neoplasms / diagnostic imaging
Kidney Neoplasms / mortality*
Kidney Neoplasms / pathology
Kidney Neoplasms / therapy
Male
Middle Aged
Predictive Value of Tests
Proportional Hazards Models
Prospective Studies
Tumor Burden
Ultrasonography, Interventional
Watchful Waiting*