AUA 2018: Characterizing the Incidence, Predictors, and Survival of Disappearing Renal Tumors from the DISSRM Registry

San Francisco, CA ( Previous literature has described spontaneous tumor regression, the disappearance of a mass without intervention, particularly with renal tumors. Clinical regression may occur as an immunologic phenomenon, but may also reflect the variable sensitivity of tumor imaging. While important, evidence regarding disappearing renal tumors (DRTs) remains sparse. The authors aimed to quantify the prevalence of DRTs among small renal masses, identify potential predictors, and characterize their survival. 

For the purpose of this study, the Delayed Intervention and Surveillance for Renal Masses (DISSRM) registry prospectively enrolled 739 patients since 2009; 374 elected active surveillance (AS). Patients undergoing AS with at least one surveillance image showing no tumor, were considered to have a DRT. Multivariable logistic regression analysis assessed predictors of DRTs and Kaplan Meier estimates measured survival. 

Of 374 AS patients, 22 (5.9%) experienced a DRT in their follow-up imaging. Average time to DRT disappearance was 1.2 years and 54.5% of tumors reappeared on subsequent CT imaging (12/22). Of the 22 DRT cases, 15 were produced by ultrasound, 5 by CT scan, and 2 by MRI. Of the 15 DRT on ultrasound, 7 (46.7%) were picked up on subsequent axial imaging. Univariate and multivariable analyses demonstrated that tumor diameter <1 cm significantly predicted DRT among the entire cohort (OR = 10.6, p=0.04) (Table 1). Lastly, DRT patients may have improved outcomes versus other AS patients (5 year survival of 100% vs. 73.2%, p = 0.06) (Figure 1). 

UroToday AUA2018 Overall Survival of Renal Tumors

In a large prospective AS cohort, the authors found that approximately 5% of patients will experience a DRT. This most often occurs when using ultrasound modalities and with small tumors <1cm. However, this does not necessarily mean that the tumor has disappeared, as approximately 50% will be visible on subsequent imaging. However, a DRT may imply low biological risk and may not require immediate axial imaging if tumor size is small. Further studies should validate this assumption.

Presented by: Arnav Srivastava, James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA
Co-Authors: Hiten Patel, Mohit Gupta, Gregory Joice, Zeyad Schwen, Ridwan Alam, Michael Gorin, Michael Johnson, Mohamad Allaf, Phillip Pierorazio, Baltimore, MD

Written by:  Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
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