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An analysis of U.S. trends and outcomes in the management of small kidney cancers now shows that surgery continues to be the most common treatment, with nephron-sparing surgery exceeding radical nephrectomy.

A study of the national Surveillance, Epidemiology, and End Results (SEER) registry (2001-2009) data also revealed that while nonsurgical management is a reasonable treatment strategy for elderly patients or those with limited life expectancy, its use remains low, William C. Huang, MD, department of urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, and colleagues report in the July JAMA Surgery.

"Although our findings support nonsurgical management as an acceptable treatment option for small kidney tumors in elderly patients or those with limited life expectancy," said Huang, "it appears that nonsurgical management of small kidney cancers remains uncommon and stable over time." He added that heightened awareness of outcomes from studies such as this may increase the use of nonsurgical management.

In the population-based cohort study, SEER cancer registry data linked to Medicare claims were used to identify patients 66 years or older with a diagnosis of primary renal-cortical tumor (<4 cm; International Classification of Diseases for Oncology, Third Edition topography codes C64 and C64.9)

Results show that overall survival (OS) was better in patients who received surgical treatment than in those who received nonsurgical management. However, only nephron-sparing surgery was associated with a benefit in cancer-specific survival (adjusted hazard ratio, 0.47; 95% CI, 0.31-0.69; P<0.001).

"...[O]ur analysis demonstrates that radical nephrectomy is no longer the treatment of choice for small kidney cancers," said Huang. "Expert guidelines for the management of small renal masses, such as those published by the American Urological Association in 2009, appear to have bolstered the paradigm shift away from radical nephrectomy toward nephron-sparing options for such tumors."

The same practice guidelines also offer ablation and surveillance as alternative treatment options for small kidney masses, noted Huang.

Analysis was performed between February 1, 2014, and December 31, 2014. The likelihood of receiving no surgery versus surgical intervention was analyzed as a function of demographic and disease characteristics, as well as the relationships between treatment approach and overall and cancer-specific survival.

Partial nephrectomy and ablation were combined and classified as nephron-sparing surgery and nonsurgical management was defined as the absence of any claim for one of these procedures in the first six months following diagnosis.

During the study period, 3,709 of the patients (61.9%) who underwent surgery had radical nephrectomy, and 2,285 patients (38.1%) had a nephron-sparing procedure.

Out of a total of 6,664 patients, the following outcomes and management trends were observed:

• 5,994 (90.0%) underwent surgery
• 670 patients (10.0%) were managed nonsurgically
• Use of radical nephrectomy decreased from 69%-42.5%
• Use of nephron-sparing surgery (partial nephrectomy and ablation) increased (from 21.5% to 49.0%)
• Proportion of patients who did not undergo surgery remained stable (9.5% and 8.5%)

During a median follow-up of 63 months (interquartile range, 43-89 months), 2,119 patients (31.8%) died, including 293 (4.4%) of kidney cancer, said the investigators.

"Our findings underscore the importance of competing causes of mortality in this population: 38.1% of patients died during the study period, but only 4.4% of patients died from kidney cancer," said Huang.

Differences in overall survival may reflect patient selection rather than a direct benefit of surgery, as highlighted by the greater risk of mortality observed soon after diagnosis in the cohort managed non-surgically, he said.

"Survival outcomes of partial nephrectomy appear to be at least equivalent and potentially superior in the short-term (median, 63 months) compared with radical nephrectomy, according to Huang. "Practically, the support for partial nephrectomy is bolstered both by patients hoping to preserve as much kidney as possible to prevent the burdens of hemodialysis and the urologist who has benefited from improvements in surgical experience."

With controls for demographic and disease characteristics as well as co-morbid conditions, patients whose care was managed non-surgically were more likely to be older, male, and nonwhite and to reside in the Western United States. Hypertension was associated with a greater likelihood of being treated surgically, and a prior non-kidney cancer diagnosis was associated with a greater likelihood of nonsurgical management, said Huang.

With a median follow-up of 57 months (inter-quartile range, 43-89 months), 136 patients (20.3%) who initially received nonsurgical treatment underwent surgery more than 6 months after diagnosis.

"Although our findings support nonsurgical management as an acceptable treatment option for small kidney tumors in elderly patients or those with limited life expectancy," said Huang, "it appears that nonsurgical management of small kidney cancers remains uncommon and stable over time." He added that heightened awareness of outcomes from studies such as this may increase the use of nonsurgical management.

"The authors establish partial nephrectomy as the new standard of treatment for small renal masses (SRMs) with the frequency of nephron-sparing surgery eclipsing that of radical nephrectomy in 2009," Joshua J. Meeks, MD, PhD, department of urology, Feinberg School of Medicine, Northwestern University, Chicago, IL., and colleagues point out in an accompanying editorial "Standard of Care for Small Renal Masses in the 21st Century" in JAMA Surgery.

Meeks noted that despite an overall increase in surgery for SRMs, the survival for patients with kidney cancer has not changed. In this study, a consistent 10.0% of tumors were actively monitored and these tumors were more likely to occur, he said.

"In older and unhealthy patients with overall survival of only 57.5% at the completion of the study, it is unclear how many masses were identified by imaging but not biopsied and therefore potentially not identified by the SEER registry," said Meeks.

"At some point," he emphasized, "every metastatic cancer must have been an SRM. As we learn more about the molecular signature of renal cancer and the mutations that drive progression, we will likely be managing SRMs differently in the near future."

The authors disclosed no relationships with industry.

• Reviewed by F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine

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