Active Surveillance Appears to Be Safe for Small Renal Masses

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The prospective Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry shows that over the intermediate term, active surveillance appears to be as safe as primary intervention for carefully selected, older, sicker patients with small renal masses.1 As the data mature, further studies will elucidate selection of the ideal candidates for active surveillance.

We can conclude that active surveillance is not inferior to primary intervention, and active surveillance is safe for small renal masses.
— Ridwan Alam, MD

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“The registry was designed to answer the question whether we need to treat patients with small renal masses. About 20% to 40% [of these masses] are found to be benign on biopsy. Active surveillance can avoid overtreatment,” explained Ridwan Alam, MD, a candidate for a Master’s degree in Public Health at Johns Hopkins University School of Medicine in Baltimore. Dr. Alam presented the intermediate results of the DISSRM registry at the 2017 Genitourinary Cancers Symposium.

Coauthor of this presentation, Mohammad E. Allaf, MD, also of Johns Hopkins, said: “Active surveillance has not been used traditionally, but with increasing evidence, the guidelines have softened their stance. Active surveillance is a completely acceptable standard of care for the elderly, infirm, and patients with comorbidities. These findings are encouraging for suitable patients who are considering active surveillance.”

“Tumors of smaller size have a low malignant potential and a low metastatic potential. The risk of metastasis is less than 1% for tumors smaller than 3 cm,” Dr. Alam explained. Tumors smaller than 4 cm may identify good candidates for active surveillance for patients who want to defer surgery and immediate treatment. Active surveillance is different from watchful waiting. Patients are tested, and intervention is recommended at evidence of disease progression.”

Mohammad E. Allaf, MD

Mohammad E. Allaf, MD

“The concern is that with active surveillance, the window of curability could be lost. Previous studies have been mainly retrospective. Active surveillance is largely underutilized, and only about 10% to 20% of eligible patients actually receive it,” continued Dr. Alam.

Current American Urological Association guidelines refer to active surveillance as a suitable option, not a strong recommendation, he explained.

Study Details

The ongoing DISSRM registry will compare outcomes with primary intervention and active surveillance and delayed intervention for small renal masses. After renal biopsy and consultation, patients can choose primary intervention (surgery or ablation) or active surveillance. Patients in the active surveillance group are imaged at enrollment and every 6 to 12 months.

Active Surveillance for Small Renal Masses

  • A prospective patient registry shows that active surveillance is equally safe as primary intervention over 3 years for small renal masses in selected patients who are elderly, have more comorbidities, and masses smaller
    than 4 cm.
  • Overall survival was better in the primary intervention group, but this may be attributed to the fact that older, sicker patients opted for active surveillance.
  • Longer-term follow-up is needed.

The study was designed as a noninferiority trial based on an intention-to-treat model. Intervention was recommended for renal masses with an elevated growth rate (> 0.5 cm/yr) or an increased tumor diameter greater than 4 cm, metastatic disease, or patient’s choice to cross over from active surveillance to intervention. Small clinical masses were defined as < 4.0 cm in diameter, clinical stage T1a, solid tumors suspicious for malignancy, and no cystic lesions. All masses were diagnosed in patients in their 60s and 70s.

Among the 615 patients enrolled in the trial since 2009, about half chose intervention, and the other half opted for active surveillance. Of the active surveillance group, 14% crossed over to intervention during the study. Median follow-up was 3 years, and 25% were followed for 5 years. “In general, patients who opted for active surveillance were older, had smaller tumors, and were in worse health,” he said.

Thus far, the median growth rate is very low, at 1 mm/yr. Eighty percent of tumors show no growth or very slow growth. It is apparent that the rate of growth is highest over the first year, Dr. Alam revealed.

Key Findings

The rate of cancer-specific survival was similar between the two 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 at 7 years (91.7% and 65.9%, respectively).

In a multivariate analysis, age and Eastern Cooperative Oncology Group (ECOG) score were the strongest predictors of all-cause mortality.

At 7 years, 76.7% of patients in the active surveillance group had some disease progression, mostly due to an elevated growth rate. No patient in the active surveillance group developed metastatic disease. “Not everyone who developed progression underwent delayed intervention,” Dr. Alam noted.

“With active surveillance, cancer-specific survival is excellent and comparable to that of primary intervention. Overall survival is worse in the active surveillance group, which can be attributed to older age and worse health in patients who opted for surveillance. 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 investigators plan to continue the study and identify biomarkers to help select patients for active surveillance. “We have developed a DISSRM Score to identify candidates for active surveillance, and we need to validate the score. Also, we plan to evaluate quality of life among primary intervention, active surveillance, and delayed intervention groups,” he ­concluded.

Additional Study Comment

Marc Smaldone, MD

Marc Smaldone, MD

“Prospective registries offer a way to move active surveillance forward and provide comparative effectiveness data for active surveillance vs primary intervention, which we are currently lacking,” said Marc Smaldone, MD, of Fox Chase Cancer Center, Philadelphia.

“The intermediate findings of this study are in line with retrospective studies showing that active surveillance is safe with intermediate-term follow-up. Growth kinetics are a clear trigger for delayed intervention,” Dr. Smaldone stated.

“Benign renal masses also grow over time. A lesion managed with active surveillance that demonstrates positive growth kinetics is the perfect candidate for a percutaneous biopsy,” he said. ■

Disclosure: Drs. Alam and Smaldone reported no potential conflicts of interest. Dr. Allaf has received institutional research funding from Progenics.


1. Alam R, Patel HD, Riffon MF, et al: Intermediate-term outcomes from the DISSRM registry: A prospective analysis of active surveillance in patients with small renal masses. 2017 Genitourinary Cancers Symposium. Abstract 430. Presented February 18, 2017.