Active surveillance is gaining ground as a strategy for managing small renal masses. According to intermediate follow-up of the prospective Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry, active surveillance appears as safe as primary intervention in selected patients. In general, active surveillance is a good option for elderly patients with comorbidities and renal masses <4 cm.
The study data were presented at the 2017 Genitourinary Cancers Symposium.
“About 20% to 40% of small renal masses are found to be benign on biopsy. With appropriate patient selection, active surveillance can avoid overtreatment,” explained Ridwan Alam, MD, from Johns Hopkins University School of Medicine in Baltimore, MD.
“The concern [among proponents of intervention] is that with active surveillance, the window of curability could be lost. Previous studies of active surveillance have been mainly retrospective. Active surveillance is largely underutilized, and only about 10% to 20% of eligible patients actually receive it,” he continued.
Tumors <4 cm have a low malignant potential and may identify good candidates for active surveillance for patients who want to defer surgery and immediate treatment, he explained. Active surveillance is different from watchful waiting, because patients are tested at intervals, and intervention is recommended at evidence of disease progression.
According to American Urological Association guidelines, active surveillance is “a suitable option” for small renal masses, but it is not a strong recommendation, Dr Alam noted.
The ongoing DISSRM registry is comparing outcomes with primary intervention with those of active surveillance and delayed intervention for small renal masses. The study was designed as a noninferiority trial. Small clinical masses were defined as <4.0 cm in diameter, clinical state T1a solid tumors suspicious for malignancy, and no cystic lesions. All masses were diagnosed in patients in their 60s and 70s.
Intervention was recommended for renal masses with an elevated growth rate (>0.5 cm/year) or increased tumor diameter >4 cm, metastatic disease, or patient’s choice to cross over from active surveillance to intervention.
After renal biopsy and consultation, patients enrolled in the study could choose primary intervention (surgery or ablation) or active surveillance. Patients in the active surveillance group were imaged at enrollment and every 6 to 12 months.
The 615 patients enrolled in the trial were evenly split between the choice of primary intervention or active surveillance. Over the course of the study, 14% of the active surveillance group crossed over to intervention. Median follow-up was 3 years, with 33% followed for 5 years or longer.
“In general, patients who opted for active surveillance were older, had smaller tumors, and were in worse health,” Dr Alam noted.
The rate of cancer-specific survival was similar between the 2 groups at 7 years—99% for primary intervention and 100% for active surveillance. Two deaths were reported, both in the primary intervention group. However, overall survival was higher in patients with primary intervention at 5 years (93% vs 80.2%, respectively) and 7 years (91.7% vs 65.9%, respectively).
Dr Alam said it was not surprising that there were more deaths in the active surveillance group because these were older, sicker patients than the primary intervention group.
At 7 years, 76.7% of patients in the active surveillance group had some degree of progression, mostly due to elevated growth rate. No patient in the active surveillance group developed metastatic disease.
“We can conclude that active surveillance is not inferior to primary intervention, and active surveillance is safe for small renal masses,” he stated.
The DISSRM is an ongoing initiative, and investigators will look for biomarkers that can inform selection of treatment.