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ORLANDO -- Following the path blazed in prostate cancer, a small but growing number of patients with small renal masses have opted for active surveillance, which has proven safe with adherence to well-defined criteria.

Data from a multi-institutional registry showed a 7-year cancer-specific survival (CSS) of 100% among 317 patients who chose active surveillance over immediate treatment of small renal masses, defined as ≤4 cm (roughly 1.5 inches). Patients who chose immediate intervention had a 7-year CSS of 99%.

Upfront treatment was associated with better overall survival (OS), but patients who opted for active surveillance were older and sicker and more likely to die of causes other than cancer, a medical student at Johns Hopkins in Baltimore, reported here at the Genitourinary Cancers Symposium.

"The cancer-specific survival is excellent and comparable in both groups," Alam said. "Overall survival is worse in the surveillance group, but that can be attributed to older age and worse health. There have been no metastasis or cancer-specific deaths in the surveillance group, despite a high number of 'progression' events."

"Looking ahead, we may need to rethink the definition of progression," he added. "We are looking at 'persistent' versus 'interval' growth. We also are considering a biomarker that might be useful in surveillance of small renal masses."

Nationally, about 20% of patients with small renal masses (<4 cm) enter active surveillance, as compared with about 5% in 2000, said , of Carolinas Healthcare System's Levine Cancer Institute in Charlotte, N.C. Similar to the situation in prostate cancer, uptake of active surveillance for small renal tumors has lagged behind in the U.S. compared with Europe and other parts of the world. As information and education improve (for patients and clinicians), he expects the proportion of patients opting for active surveillance to increase.

"We know that if a mass is a centimeter to a centimeter and a half, we know the chances that it will metastasize in the next 3 years is 1% or 2%," said Graham, who is an expert for the American Society of Clinical Oncology. "If someone is 70- to 75-years-old, has a potential life expectancy of less than 5 years, we're not helping by treating that. In fact, we run a higher risk of hurting those people than helping them."

"We're recognizing the biology of the disease, and knowing whether this is going to be something that hurts or limits the life of the person," he added. "If it's not going to do that, why put the patient through the hassles, the difficulties, the expense of treating it?"

Background

Active surveillance gained a foothold in urology and oncology as a result of data showing frequent biopsy and surgical removal of what proved to be benign small renal masses. From 2000 to 2009, the number of increased by 82%.

In contrast to prostate cancer, wherein aggressiveness is defined by several pathologic and clinical features, multiple studies demonstrated a strong association between the size and aggressiveness of renal masses. Alam shared data from an as-yet unpublished systematic review showing the likelihood of aggressive pathology (grade 3/4) increased from 6.9% for renal masses 0 to 2 cm to 11% for lesions 2 to 3 cm to 17% for masses 3 to 4 cm.

Renal masses <4 cm have a metastasis risk <2%, decreasing to <1% for masses <3 cm.

"The data suggest that tumors 4 cm or less may be good candidates for active surveillance," said Alam.

The systematic review, involving 73 published articles and almost 1,800 patients, showed a median CSS of 100%, median metastasis-free survival of 99%, and OS of 89% in patients who entered active surveillance for small renal masses.

The American Urological Association, European Association of Urology, and National Comprehensive Network all cited active surveillance as a reasonable option for selected patients: small tumor size, limited life expectancy, high comorbidity burden. Yet, found evidence of a trend toward increased use of partial nephrectomy and ablative techniques for management of renal masses ≤4 cm.

Alam reported findings from an analysis of data from the Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry, which began accumulating data in 2009 from Johns Hopkins, Columbia University in New York City, and Beth Israel Deaconess Medical Center in Boston. Patients with renal masses ≤4 cm receive counseling about management options and then decide whether to have immediate intervention or to defer intervention and enter active surveillance.

Study Results

The analysis comprised 615 patients, 317 of whom initially opted for surveillance. Patients who choose active surveillance are offered biopsy at enrollment, and then axial imaging with CT or MRI, followed by ultrasound or axial imaging at 6- to 12-month intervals. Intervention is recommended with evidence of lesion progression, including growth rate >0.5 cm/year, lesion diameter >4.0 cm, or metastasis. Patients also may opt to cross over to deferred intervention.

Patients included in the analysis had a median follow-up of 3 years, and 126 patients had follow-up ≥5 years. Alam said 45 patients (14.2%) had delayed intervention during follow-up.

Patients who opted for surveillance were older (70.8 versus 61.8, P<0.001), had worse health (5.8% versus 2.4% ECOG performance status 2-4, P=0.02; 43.5% vs 60.1% Charlson comorbidity 0, P<0.001), and smaller tumors (diameter 1.8 versus 2.5 cm, P<0.001; volume 3.3 vs 12.1 cm³, P<0.001).

An analysis of 251 patients on active surveillance showed an annual tumor growth rate of 0.09 cm/year. Alam reported that 30.8% of the patients had tumor shrinkage, 10.7% had annual tumor growth of 0, 37.7% had growth of 0-0.5 cm/year, and 20.8% had >0.5 cm/year.

The CSS was virtually identical throughout follow-up in the active surveillance and immediate intervention groups. OS was about 98% in both groups at 2 years, but thereafter was higher in the intervention group: 92.7% versus 78.5% at 5 years and 85.1% versus 62.8% at 7 years (P=0.001).

A multivariate analysis identified age and ECOG performance status as the only independent predictors of OS.

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