Collecting duct carcinoma (CDC) is biologically more aggressive than clear cell renal cell carcinoma (ccRCC). We tested for differences in cancer specific mortality (CSM) rates according to CDC vs. ISUP (International Society of Urological Pathology) 4 ccRCC histological subtype. We hypothesized that the survival disadvantage still applies, even after most detailed adjustments.
Within Surveillance, Epidemiology, and End Results database (2004–2018), we identified 380 CDC vs. 6273 ISUP 4 ccRCC patients of all stages. Propensity score matching (age, sex, race/ethnicity, T, N, and M stages, nephrectomy, and systemic therapy status), Kaplan-Meier plots and multivariable Cox regression models were used.
All 380 CDC were matched (1:2) with 760 ISUP4 ccRCC patients. Prior to matching CDC patients exhibited higher rates of lymph node invasion (37.6 % vs. 14.7 %, p < 0.001), and of distant metastases (40.8 % vs. 30.4 %, p < 0.001). Systemic therapy rates were higher in CDC (29.5 % vs. 20.5 %, p < 0.001). However, nephrectomy rates were higher in ISUP4 ccRCC patients (97.5 % vs. 84.7 %, p < 0.001). After matching, in multivariable Cox regression models addressing CSM, CDC was associated with a HR of 1.5 ( p < 0.001) in the overall population vs. 1.9 ( p = 0.014) in stage I-II vs. 1.4 ( p = 0.022) in stage III vs. 1.6 in stage IV ( p < 0.001), relative to ISUP4 ccRCC.
CDC patients exhibited 40–90 % higher CSM than their ISUP4 ccRCC counterparts in the overall analysis, as well as in stage specific analyses. The CSM disadvantage applies despite higher rates of systemic therapy in CDC patients.
- • Collecting duct carcinoma is stated as a high-grade tumor by ISUP.
- • The present study firstly compared collecting duct and ISUP 4 clear cell renal carcinoma.
- • Collecting duct carcinoma exhibited 40–90 % higher mortality according to stage.
- • The survival disadvantage applies even with the strictest available statistical methodology.
Collecting duct carcinoma (CDC) of the kidney is a rare histological subtype, which account for 1–2 % of all renal malignancies . Compared to clear cell renal cell carcinoma (ccRCC), CDC exhibits more aggressive behavior and presents at more advanced stage . Despite these established notions, contemporary epidemiological studies addressing the magnitude of differences in cancer specific mortality (CSM) between CDC and ccRCC are unavailable. Indeed, historical comparisons included ccRCC patients of all grades . Such bias is clearly against the International Society of Urological Pathology (ISUP) recommendations that qualify CDC as a high-grade tumor that should invariably be compared with high-grade ccRCC . Moreover, historical reports relied on limited sample sizes of CDC that ranged from 41 to 160 patients . The exception consists of Sui et al. , who focused on the largest ever examined CDC population of 577 patients. However, their analyses did not compare mortality rates between CDC and ccRCC.
We addressed this void and compared CSM between CDC and ccRCC. Unlike previous analyses, the comparison relied on CDC and ISUP4 ccRCC, according to ISUP recommendations. Moreover, due to very important sample size differences between the two cohorts, we relied on propensity score matching (PSM) to most closely simulate a randomized control trial . We hypothesized that survival disadvantage associated with CDC histological subtype applies even after most detailed adjustments, including PSM. We relied on Surveillance, Epidemiology, and End Results (SEER) database (2004–2018).