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SAN ANTONIO -- Delaying surgery for small renal masses in favor of a period of surveillance did not adversely affect feasibility or outcomes of subsequent nephron-sparing interventions, a large retrospective study showed.

A similar proportion of patients had nephron-sparing interventions with immediate or delayed surgery. Perioperative complications, surgical outcomes, and survival also did not differ between patients who had immediate or delayed surgery, reported Michael Wang, MD, of Wayne Health in Detroit, at the American Urological Association (AUA) annual meeting.

"Basically, we are not taking a disease that previously was easy to treat and making it harder to treat in the future and preventing us from performing nephron-sparing interventions," said Wang.

AUA moderator Alexander Kutikov, MD, of Fox Chase Cancer Center in Philadelphia, said the study produced "a very important message, that putting patients on active surveillance -- there's really no downside. You can always do that partial [nephrectomy] later on."

An unidentified member of the audience questioned whether defining delayed intervention as a minimum wait of 90 days was appropriate "recognizing the very slow growth rate of these lesions, 3 to 5 millimeters per year. Many surgeons in this room will tell you that their OR [operating room] backlog is greater than 3 months. It seems like a short timeframe to define delayed intervention. Why not use beyond 1 year?"

"That's a good point and could be something to look into," Wang acknowledged. "The median time to intervention in the delayed group was 410 days as opposed to 40 days for [immediate surgery]."

By way of introduction, Wang noted that diagnosis of renal masses has increased substantially in recent years, possibly as a result of increased use of cross-sectional imaging. However, the rise has been driven by detection of small, asymptomatic renal masses (<7 cm), which account for 57% of all new diagnoses. The mean size of cT1 tumors at diagnosis has decreased in recent years from 4.1 to 3.6 cm.

"As a result, active surveillance has really become an integral tool in our armamentarium for the management of small renal masses," he said.

Several large clinical series have shown that about a third of patients with cT1 tumors eventually undergo delayed surgical intervention, whether a result of tumor growth or patient/physician preference, Wang added. Whether that delay has a negative impact on the ability to perform, or the outcomes of, nephron-sparing surgery was the primary objective of the study.

Wang reported findings from an analysis of the (MUSIC) database, which began as an initiative to improve surgical outcomes in prostate cancer and has since expanded to kidney stone interventions and small renal masses. The kidney initiative comprises 20 urology practices, more than 100 urologists, and six patient advocates. MUSIC currently comprises data on more than 5,000 small (T1) renal mass cases.

The analysis included 2,156 patients with small renal masses, 2,009 who had immediate surgery and 147 who had delayed intervention, defined as more than 90 days after initial assessment. The median time to immediate intervention was 43 days and median time to delayed intervention was 410 days. Median follow-up was 28 months for the patients who had immediate surgery and 32 months for those who had delayed intervention.

In the immediate and delayed groups, 70-75% of patients subsequently underwent nephron-sparing interventions. The data showed no significant difference in blood loss ≥500 mL, use of transfusion, warm ischemic time ≥30 minutes, prolonged length of stay, emergency department visits within 30 days of intervention, or readmission within 30 days.

Analysis of oncologic outcomes showed no difference in benign pathology at surgery. Positive surgical margins occurred more often in patients who had immediate surgery (5.1% vs 0%, P=0.008).

Survival free of progression to stage IIIb chronic kidney disease was similar between the two groups, and overall survival was about 95% in both groups.

Wang acknowledged the retrospective nature of the study as a limitation, along with the limited number of patients with delayed intervention, and the relatively brief follow-up of about 2 years.

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