Purpose
Cryoablation is done in select patients with pT1b nonmetastatic renal cell carcinoma without convincing proof of efficacy. Our aim was to test for differences in the cancer specific mortality rate for cryoablation and partial nephrectomy in T1b nonmetastatic renal cell carcinoma cases.
Materials and Methods
In the 2004 to 2015 SEER (Surveillance, Epidemiology, and End Results) database we identified 5,763 patients with a T1b tumor treated with cryoablation or partial nephrectomy. Modeling relied on multivariable logistic regression models predicting cryoablation vs partial nephrectomy. After 1:2 ratio propensity score matching between patients treated with cryoablation vs partial nephrectomy we used cumulative incidence plot and competing risks regression to test differences in cancer specific mortality and other cause mortality rates.
Results
Relative to the 5,521 patients who underwent partial nephrectomy the 242 treated with cryoablation were older, had smaller tumors and more frequently harbored unclassified renal cell carcinoma of low or unknown grade. Median followup was 38 months. In multivariable logistic regression models predicting cryoablation vs partial nephrectomy more advanced patient age was an independent predictor (OR 1.03; p=0.007). After propensity score matching and other cause mortality adjustment the 5-year cancer specific mortality rate was 2.5-fold higher after cryoablation than after partial nephrectomy (p=0.03). Conversely after propensity score matching and cancer specific mortality adjustment the 5-year other cause mortality rate was similar to that of partial nephrectomy after cryoablation (HR 1.45, p=0.12). The major limitation of this study was the lack of recurrence and metastatic progression data.
Conclusions
The current findings demonstrated a 2.5-fold increase in cancer specific mortality when cryoablation was performed in patients with pT1b renal cell carcinoma. This observation should be interpreted as a contraindication to cryoablation outside clinical trials or institutional protocols.
Cryoablation is recommended by AUA [1] and EAU [2] guidelines for patients with T1a non metastatic renal cell carcinoma. However, its use in non-metastatic T1b renal cell carcinoma patients is still under debate. Trying to shed some light on the subject, we analysed more than 5,700 cases of non-metastatic pT1b renal tumors treated in the 11-year period of 2004 to 2015 within the SEER national database. We observed a 2.5-fold increase in cancer-specific mortality (CI: 1.08-5.63, p=0.03) after cryoablation (n=228) relative to partial nephrectomy (n=434) in T1b patients [3]. This disadvantage persisted after several statistical adjustments for potential confounding within this population-based retrospective patients’ cohort. Our analysis could not address several important endpoints, such as recurrence rates or metastasis-free survival. Nonetheless, despite this populations’ data limited availability of data points, our results report concern about cryoablation use in T1b patients instead of partial nephrectomy.
References:
[1] Campbell S, Uzzo RG, Allaf ME, Bass EB, Cadeddu JA, Chang A, et al. Renal Mass and Localized Renal Cancer: AUA Guideline. J Urol 2017;198:520–9. doi:10.1016/j.juro.2017.04.100.
[2] Renal Cell Carcinoma EAU Guidelines on. 2018.
[3] Pecoraro A, Palumbo C, Knipper S, Mistretta FA, Tian Z, Shariat SF, et al. In Non-Metastatic pT1b Kidney Cancer Patients Cryoablation Predisposes to Higher Cancer Specific Mortality Relative to Partial Nephrectomy. J Urol 2019:101097JU0000000000000460. doi:10.1097/JU.0000000000000460.