Trends, Outcomes in Localized RCC With Sarcomatoid Dedifferentiation

Researchers presenting at the 2023 American Society of Clinical Oncology Genitourinary Cancers Symposium highlighted the largest retrospective characterization of localized renal cell carcinoma (RCC) with sarcomatoid dedifferentiation (sRCC).

Their results showed that sRCC has increased in prevalence, while the number of patients presenting with synchronous metastases has decreased.

sRCC is known as a subtype of RCC with poor prognosis and a high rate of synchronous metastases at presentation. However, outcomes in a contemporary cohort of patients with localized sRCC are not well characterized.

Luke Wang, MD, and colleagues designed a population-based study to determine the clinical characteristics, temporal trends in prevalence, and survival outcomes in patients with localized sRCC. Using the National Cancer Database, researchers extracted data of 440,230 patients aged at least 18 years with RCC from 2004 to 2019. Among these, 3.3% (n=14,713) had sarcomatoid dedifferentiation.

Multivariable Cox proportional-hazards regression was used to determine the impact of clinical and pathologic characteristics on all-cause mortality (ACM) in patients with nonmetastatic disease. Actuarial overall survival (OS) was computed with Kaplan-Meier analysis, and a subanalysis was performed for patients with American Joint Committee on Cancer Prognostic Stages I-III.

Results of the analysis showed that sarcomatoid dedifferentiation increased from 1.9% in 2004 to 4.1% in 2019, with an average annual percentage change (AAPC) of 0.06 (P<.001). sRCC with synchronous metastasis decreased from 48.7% in 2004 to 38.7% in 2019, with an AAPC of -0.028 (P<.001).

Cox regression for nonmetastatic sRCC showed ACM was associated with age (hazard ratio [HR], 1.02; P<.001), Charlson comorbidity (HR, 1.21; P<.001), tumor size (HR, 1.04; P<.001), cN1 (HR, 1.01; P<.001), collecting duct (HR, 2.33; P=.002), medullary (HR, 4.7; P=.031), and RCC unspecified histology (HR, 1.46; P<.001). ACM was inversely associated with partial (HR, 0.19; P<.001) and radical (HR, 0.3; P<.001) nephrectomy.

Furthermore, researchers found that in nonmetastatic sRCC, 5-year OS was 52.9%. Substratification showed 5-year OS of 72.9% for Stage I, 60.4% for Stage II, and 40.9% for Stage III sRCC (P<.001).

“Outcomes in patients with localized sRCC are poor and associated with patient comorbidity, stage, and associated histological findings,” they concluded. “Future studies investigating the underlying biology driving increased sarcomatoid dedifferentiation despite generalized downward stage migration in RCC are requisite.”