No contemporary data allows ascertaining whether ablation and observation might predispose patients with T1a renal cell carcinoma (RCC) to higher cancer specific mortality (CSM) relative to partial nephrectomy (PN).1 This lack of comparative data is particularly important for elderly individuals who are at high risk of other-cause mortality (OCM). Within the Surveillance, Epidemiology, and End Results database, we selected T1a RCC patients treated with ablation, observation or PN. Two group comparisons were created, namely ablation vs. PN and observation vs. PN. In each comparison, patients were further stratified in two groups according to age ((<65 and ≥65 years). A 1:1 propensity score matching and multivariable competing risks regression models were applied.2
After matching, patients treated with ablation exhibited a 2-fold increase in CSM, compared to those treated with PN. Nonetheless, after stratification according to age, the CSM disadvantage disappeared in individuals <65 years, but persisted in those ≥65 years, however at a lower rate (HR 1.8). These findings suggest an adequate selection process for patients treated with ablation. However, we were unable to adjust for subsequent therapies that may have been delivered to patients with disease recurrence and/or progression, such as surgery, radiation and/or medical therapies. It is possible that elderly patients benefitted from fewer opportunities for treatment of recurrence and/or progression, relative to younger patients. In consequence, the differences between ablation and PN in young patients may have been obliterated by the differential use of these subsequent therapies that favored younger patients. On the other hand, a different scenario applied to observation. Here, after matching, patients treated with observation showed a 3-fold increase in CSM, which was equally operational in younger and older patients, when subgroup analyses were performed. However, OCM rates that were substantially higher in patients treated with observation, emphasizing the important difference that exists between observation and PN.
In conclusion, from a clinical perspective, ablation may be considered as an alternative to surgery in T1a RCC patients, due to a modest CSM disadvantage. Conversely, observation is associated with an increased risk of CSM. Therefore, observation may be reserved for patients at elevated risk for OCM, for whom the morbidity associated with surgery may be higher.
Written by: Carlotta Palumbo, MD and Pierre I. Karakiewicz, MD, Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Center, Montreal, Quebec, Canada. Twitter: @CPalumbo87, @sophieknipper, @AngelaPecoraro3, @DrShariat, @aleantonellibs1, @pikarakiewicz,
References:
1. Pierorazio PM, Johnson MH, Patel HD, Sozio SM, Sharma R, Iyoha E, et al. Management of Renal Masses and Localized Renal Cancer: Systematic Review and Meta-Analysis. J Urol 2016;196:989–99. doi:10.1016/j.juro.2016.04.081.
2. Palumbo C, Mistretta FA, Knipper S, Mazzone E, Pecoraro A, Tian Z, et al. Assessment of local tumor ablation and non-interventional management versus partial nephrectomy in T1a renal cell carcinoma. Minerva Urol Nefrol 2019. doi:10.23736/S0393-2249.19.03496-9.
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