Impact of Tumor Size on Cancer-Specific Mortality Rate After Local Tumor Ablation in T1a Renal-Cell Carcinoma

Abstract

Introduction:

Institutional studies suggested that tumor size (TS) might be an independent predictor of recurrence after local tumor ablation (LTA). However, limited data exist to ascertain whether a larger TS may also predispose to a worse cancer-specific mortality (CSM) rate.

Materials and Methods:

Patients treated with LTA for T1a nonmetastatic renal-cell carcinoma were identified within the Surveillance, Epidemiology, and End Results (SEER) database (2004–2015). Estimated annual percentage change (EAPC) methodology, cumulative incidence plots, and multivariable competing risk regression (CRR) models before and after the 1:1 ratio propensity score (PS) adjustment were used to compare LTA for TS ≤30 mm vs TS >30 mm. A comparison of cryosurgery vs thermal ablation according to TS was also performed.

Results:

Of 3946 LTA patients, 2974 (75.3%) patients harbored TS ≤30 mm vs 972 (24.7%) harbored TS >30 mm. The latter was significantly older (median age 67 years vs 71 years, p < 0.001), compared with TS ≤30 mm. No differences were recorded in annual rates over time. In unmatched CRR models, after adjustment for other-cause mortality (OCM) rate, LTA for TS >30 mm showed a worse 5-year CSM rate (hazard ratio [HR] 2.3, p < 0.001), relative to TS ≤30 mm. In PS- and OCM rate-adjusted CRR models, LTA for TS >30 mm still showed a worse 5-year CSM rate (HR 2.86, p < 0.001), relative to TS ≤30 mm. Thermal ablation was associated with a higher 5-year CSM rate, compared with cryosurgery (7.6% vs 3.9%, p = 0.02), but only when TS was >30 mm.

Conclusions:

TS >30 mm is an independent predictor of higher 5-year CSM rates in patients treated with LTA, even after adjustment for OCM rate. In consequence, when LTA is considered, it ideally should be performed for TS ≤30 mm.