Population-based comparative effectiveness of nephron-sparing surgery vs ablation for small renal masses

To determine, in a population-based cohort, if disease-specific survival (DSS) was equivalent in patients undergoing ablation vs nephron-sparing surgery (NSS) for clinical stage T1a renal cell carcinoma (RCC).

A retrospective cohort study was performed using patients from the Surveillance, Epidemiology and End Results cancer registry with RCC < 4 cm and no evidence of distant metastases, who underwent ablation or NSS. Kaplan-Meier and Cox regression analyses were performed to determine if treatment type was independently associated with DSS.

Between 1998 and 2007, a total of 8818 incident cases of RCC were treated with either NSS (7704) or ablation (1114). The median (interquartile range) follow-up was 2.8 (1.2-4.7) years in the NSS group and 1.6 (0.7-2.9) years in the ablation group, although 10% of each cohort were followed up beyond 5 years. After multivariable adjustment, ablation was associated with a twofold greater risk of kidney cancer death than NSS (hazard ratio 1.9, 95% confidence interval 1.1-3.3, P= 0.02). Age, gender, marital status and tumour size were also significantly associated with outcome. The predicted probability of DSS at 5 years was 98.3% with NSS and 96.6% with ablation.

After controlling for age, gender, marital status and tumour size, the typical patient presenting with clinical stage T1a RCC, who undergoes ablation rather than NSS, has a twofold increase in the risk of kidney cancer death; however, at 5 years the absolute difference is small, and may only be realized by patients with long life expectancies.