Outcomes and Predictors of Recurrence and Survival in Surgically Resected Localized Chromophobe Renal Cell Carcinoma: Results from the Canadian Kidney Cancer Information System (CKCis).

Chromophobe RCC (chRCC) represents 5-10% of all RCC; however, data regarding outcomes and predictors of recurrence and survival in localized disease are limited. The Canadian Kidney Cancer Information System (CKCis) is a multi-institutional prospective cohort. Patients who had surgical resection for clinically localized chRCC between January 2011 and July 2024 were included. Descriptive statistics were used, and cancer recurrence and time to death were estimated using Kaplan-Meier curves. Associations between baseline and tumour characteristics and recurrence and survival were assessed using Cox proportional hazards models. The study cohort included 790 patients. Median follow-up was 4.9 years, mean age was 57.8 years and 57.5% were male. Partial nephrectomy occurred in 52.7% and radical in 47.3%. Recurrence-free survival was 93.6% at 5 years and 90.2% at 10 years. In the 45 patients who recurred, 40 had metastatic disease, 3 had local recurrences, and 2 had new contralateral disease. Predictors of recurrence included a higher pT stage, sarcomatoid features, positive margins, and tumour necrosis. Overall survival was 94.5% at 5 years and 83.7% at 10 years. Predictors of death included high pT stage, increase in pathological size, and increasing age at diagnosis. In this large Canadian cohort, patients with surgically resected, localized chRCC had favourable 5- and 10-year oncologic outcomes. These favourable outcomes are a reminder that not all RCC patients with non-clear cell histologies should be pooled together as a single entity. There is, however, a subgroup of patients with less favourable outcomes who should be the focus of future research that aims to prevent recurrence and RCC death.