Some variant histological subtypes of renal cell carcinoma (RCC) are associated with an increased risk of cancer-specific mortality (CSM) compared with the clear-cell RCC subtype, according to investigators.

Of 69,785 RCC patients in the Surveillance, Epidemiology, and End Results registry, 2495 had variant histology. Among variant cases, 70.1% were sarcomatoid, 11.2% collecting duct, 7.6% mesenchymal, 3.8% neuroendocrine, 2.9% renal medullary, 2.5% mucinous tubular and spindle cell (MTSCC), and 2.0% rhabdoid tumors.

Tumors with variant histology displayed more advanced TNM stage at presentation than clear-cell tumors, Marina Deuker, MD, of University Hospital Frankfurt in Germany, and colleagues reported in The Journal of Urology. A higher proportion of cancers with variant histology compared with clear-cell histology were clinical T3/T4 (range 31.9 to 67.3% vs 22.8%); N1 (range 13.7 to 54.1% vs 3.7%); and M1 (range 24.5 to 73.6% vs 10.9%).

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In addition, the investigators found a significant 1.6- and 1.8-fold higher CSM risk for collecting duct and sarcomatoid subtypes, respectively, and 1.7- and 1.5-fold increased CSM risk for renal medullary and rhabdoid subtypes, respectively, compared with grade 4 clear cell RCC (per the International Society of Urologic Pathologists grading system). The researchers found similar cancer death rates for mesenchymal, neuroendocrine, and MTSCC subtypes.

In a separate analysis, Dr Deuker’s team found a 20% higher CSM risk after partial nephrectomy compared with radical nephrectomy among patients with the sarcomatoid subtype. The infiltrative nature of these tumors may make it difficult to achieve negative surgical margins, they noted. A paucity of cases precluded analyses of nephrectomy for other subtypes.

According to the authors, this study is the largest and most contemporary series of the 7 variant histology subtypes in RCC.

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Deuker M, Stolzenbach F, Rosiello G, et al. Renal cell carcinoma: comparison between variant histology and clear cell carcinoma across all stages and treatment modalities [published April 6, 2020]. J Urol. doi: 10.1097/JU.0000000000001063