Management of Small Kidney Cancers in the New Millennium: Contemporary Trends and Outcomes in a Population-Based Cohort.

IMPORTANCE: With the significant downward size and stage migration of localized kidney cancers, the management options for small kidney cancers have expanded and evolved.

OBJECTIVE: To describe trends and outcomes in the management of small kidney cancers in the first decade of the new millennium.

DESIGN, SETTING, AND PARTICIPANTS: Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked to Medicare claims were used to identify patients 66 years or older with a pathologically confirmed small kidney cancer (<4 cm) diagnosed between January 1, 2001, and December 31, 2009; analysis was performed between February 1, 2014, and December 31, 2014. Multivariable logistic regression was used to assess the likelihood of nonsurgical management vs surgical intervention. Cox proportional hazards regression was used to assess the relationships between treatment approach and overall and cancer-specific survival. The effect of treatment approach on cancer-specific survival was analyzed in a competing risks framework.

MAIN OUTCOMES AND MEASURES: The likelihood of receiving no surgery vs surgical intervention as a function of demographic and disease characteristics, as well as the relationships between treatment approach and overall and cancer-specific survival.

RESULTS: Of 6664 patients, 5994 individuals (90.0%) had surgical treatment; the care of 670 patients (10.0%) was managed nonsurgically. Use of radical nephrectomy decreased over time (from 69.0% to 42.5%), and the use of nephron-sparing surgery (partial nephrectomy and ablation) increased (from 21.5% to 49.0%); the 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) (follow-up for vital status through December 31, 2011), 2119 patients (31.8%) patients died, including 293 individuals (4.4%) of kidney cancer. Although overall survival was better in patients who received surgical treatment, 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 < .001).

CONCLUSIONS AND RELEVANCE: Surgery continues to be the most common treatment for patients with small kidney cancers. The use of nephron-sparing surgery exceeds radical nephrectomy in patients who receive surgery. Although our findings suggest that nonsurgical management is acceptable for certain patients, use of this approach remains low.