ORLANDO—A new objective scoring system can identify patients with small renal masses (SRM) who are the most suitable candidates for active surveillance (AS), researchers reported at the American Urological Association 2014 annual meeting.

The scoring system was tested in the prospective, multi-institution Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) Registry, which enrolled patients with SRM 4.0 cm or less in diameter who chose AS or intervention. Patients who opted for AS followed an imaging protocol every 4-6 months for 2 years, then 6-12 months for 3 years.

Investigators developed objective criteria from the existing literature and refined these criteria based on experience with the registry. Researchers assigned points for age older than 65 years (1 point), age older than 75 years (2), ECOG greater than 1 (2), greatest tumor diameter less than 3 cm (1) or less than 2 cm (2), low-complexity RENAL nephrometry score (1), dementia (2), or a modified cardiovascular index (CVI: 0, 1, or 2).

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To calculate the CVI, patients with congestive heart failure or more than 1 of the following disease states (cerebrovascular disease, coronary artery disease, peripheral vascular disease, chronic obstructive pulmonary disease, chronic kidney disease, or diabetes mellitus) are assigned 2 points; patients with 1 risk factor are assigned 1 point. A higher score indicates improved suitability for AS. The maximum DISSRM score is 11.

At 57 months, 438 patients were enrolled. Of these, 177 elected AS, 261 opted for primary intervention, and 21 crossed over from AS to intervention. Median DISSRM scores for the intervention and AS patients were 3 and 4, respectively. In all, 67% of intervention patients and 25% of AS patients had a score of 3 or less; 19% and 49%, respectively, had a score of 4 or higher.

In the AS and primary intervention groups, the overall survival rates were 96.0% and 98.1%, respectively, at 2 years and 93.2% and 87.8% at 4 years. Disease-specific survival was 100% and 99% at 4 years, with only 1 patient who underwent intervention dying of renal cell cancer. None of the between-group differences were statistically significant.

“Based on equivalent intermediate-term cancer-specific outcomes, the DISSRM score may act as an easy-to-calculate surrogate for competing risk mortality in patients with SRM,” the researchers concluded.