Surveillance called 'reasonable' for small renal masses

Orlando, FL-Active surveillance appears to be a reasonable option for older patients with small renal masses, most of which are discovered during imaging for unrelated conditions, says the author of a recent study.

In such patients, cancer-specific survival does not seem to be compromised compared with surgical intervention, according to an examination of the national Surveillance, Epidemiology, and End Results (SEER) cancer registry linked to Medicare claims. The evidence also suggests that surgery in patients with small renal masses may adversely impact non-oncologic outcomes over time, first author William C. Huang, MD, said at the Genitourinary Cancers Symposium in Orlando, FL.

Nearly two-thirds of renal masses detected are <4 cm, with most being incidental findings on imaging procedures unrelated to the kidney, said Dr. Huang, assistant professor of urologic oncology at New York University Langone Medical Center, New York. They represent a heterogeneous group of tumors with varying malignant potential, for which surgery has been the standard treatment.

“Over the past decade, we’ve discovered that perhaps these tumors don’t need to be removed because removal has not resulted in improvements in cancer-specific outcomes. We’ve also recognized that kidney cancer surgery has an impact on kidney function and may adversely impact non-oncologic outcomes such as cardiovascular events and mortality,” he said. “We speculated that perhaps like other malignancies such as prostate cancer, sicker and older patients with small kidney cancer may not benefit from undergoing surgery.”

From the SEER database linked with Medicare claims, 8,317 subjects 66 years of age and older who received surveillance or surgery for small renal masses diagnosed between 2000 and 2007 were identified. A total of 7,148 had a pathologic diagnosis of kidney cancer, 78% of whom underwent surgery and 22% who underwent surveillance. The median follow-up for survivors was 64 months in the group that had surveillance and 57 months in those who underwent surgery. Of the patients who had surgical intervention, 65% received radical nephrectomy and 35% received nephron-sparing surgery (partial nephrectomy or ablative therapy).

The use of surveillance, defined as no treatment within the first 6 months following diagnosis, increased over time but not among those with a pathologic diagnosis of kidney cancer. Patients undergoing surveillance were more likely to be male and non-Caucasian and live in urban areas or the South or West regions.

Approach not linked with mortality risk

Over a median follow-up of 59 months, 3% of subjects died from kidney cancer. The treatment approach was not associated with the risk of death from kidney cancer.

“This is not surprising, since there are a lot of data to suggest that many patients will not die of these kidney tumors,” Dr. Huang said. “The dilemma is that even though 3% is low, we can’t reliably figure out at this time, even with biopsy and imaging, which 3% are going to die of kidney cancer. Therefore, we can’t extrapolate these findings to younger patients or patients who have a normal lifespan.”

About one-fourth (24%) of patients had at least one cardiovascular event. Surveillance was associated with a significantly lower risk of a cardiovascular event, with a hazard ratio of 0.51 (p<.00001).

One-fifth of the patients died: 24% in the surgery group and 13% in the surveillance group.

“Surveillance was associated with a significantly lower risk of death from any cause over time, and as time went on this difference became more and more apparent,” said Dr. Huang.

At 6 months, the adjusted hazard ratio (HR) for death for surveillance was increased at 1.27, which was not significant. However, after 6 months, surveillance was associated with a significantly decreased risk of death: The adjusted HR was 0.70 at months 7 to 36, and 0.37 after month 36. Radical nephrectomy was associated with poorer cardiovascular and overall survival outcomes compared with partial nephrectomy and surveillance.

“Several limitations are worth noting,” Dr. Huang added. “Since this is a retrospective cohort study, some of the results may be a product of selection bias not controlled for in the study. The study also doesn’t provide us with guidance regarding appropriate surveillance protocols.”UT