Mucinous tubular and spindle-cell carcinoma of the kidney: Clinical features, genomic profiles, and treatment outcomes.

Abstract Background Mucinous tubular and spindle-cell carcinoma (MTSCC) is a rare kidney cancer subtype with limited cases reported in the literature. We report on outcomes of 25 patients with this variant who were managed at our institution. Materials and Methods The institution database was queried, and clinical data extracted for patients with MTSCC. Molecular features examined included next-generation sequencing with Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets and allele-specific copy number analysis using the Fraction and Allele-Specific Copy Number Estimates from Tumor Sequencing (FACETS) algorithm in a subset of patients. Results All patients underwent primary tumor-directed therapy (nephrectomy = 23, cryoablation = 2). Metastases were diagnosed in 6 patients (24%), 3 (12%) of whom had de novo metastatic disease. Five of 6 patients with metastatic disease had high-grade histological features compared with 0 of 19 nonmetastatic patients (83% vs. 0%; P Conclusion MTSCC is characterized by localized tumors treated successfully with primary tumor-directed therapy. However, patients with high-grade histological features were more likely to develop metastatic disease with limited responses to standard therapies.