ORLANDO, FL USA (UroToday.com) - Despite increased detection and surgical intervention, mortality curves for kidney cancer remain flat, raising the question of whether there is an oncologic benefit to resecting all T1a lesions. This fact has fueled interest in the use of active surveillance (AS) for management of these masses. To date, much of our understanding of the safety of AS comes from retrospective studies. For this reason, the Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry was launched in 2009, with the intention to bring the clarity of a prospective study to the issue of AS for small renal masses. It was designed and powered as a non-inferiority study to detect a 5% difference in cancer-specific survival between AS and definitive treatment. The assignment is patient-driven and not randomized.
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At the time of analysis, 438 patients had been enrolled with 177 electing for AS, 261 deciding on surgical management initially, and 21 who crossed over from AS to intervention. They found that patients on AS tended to be older with poorer functional status, "more comorbidities and had smaller, more complex tumors." The overall median follow-up period was 2.04 years (maximum of 5 years). Progression was defined as a growth rate of > 0.5 cm/year, a greatest tumor diameter > 4 cm, development of metastases, or cross over to the intervention group. In total, 35 patients progressed, with 21 of them doing so due to cross over (16 elective, 5 due to progression).
The overall survival among patients under AS and those receiving intervention was "96.0% and 98.1% at 2, and 93.2% and 87.8% at 4 years respectively (log-rank, p=0.65)." At 4 years, disease-specific survival was 100% and 99% for patients under AS and receiving intervention, respectively. At the same time point, recurrence-free survival was 95.4% in the intervention cohort, while "progression-free survival in the AS cohort was 57.5% at 2 and 53.0% at 4-years." There were no cases of progression to metastatic disease among the AS cohort.
From these results, the group concluded that in a well-selected cohort, cross over from AS to intervention is a rare event, occurring in approximately 5% of cases. Following Dr. Ball's presentation, an active discussion took place. Dr. Ball mentioned that through their trial it appears urologists are doing well in helping appropriate patients to choose AS, but that better imaging techniques need to be developed to improve the ability to better individualize treatment for patients with small renal masses. It will be very interesting to follow the progress of this registry and how it will be able to impact decision-making with respect to enrolling patients in active surveillance versus early extirpative therapy.
Presented by Mark Ball at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
Baltimore, MD USA
Written by Martin Hofmann, MD, University of California (Irvine), and medical writer for UroToday.com