Retrospective Review of Clear Cell and Non-Clear Cell Renal Carcinomas: Characteristics and Course in the Pre-TKI (Tyrosine Kinase Inhibitor) and Post-TKI Era.

Background:  Renal cell carcinoma (RCC) confers a lifetime risk of 1.6% of developing cancers. Early, localized cancers have high cure rates after surgical treatment, but locally advanced/distant metastatic disease remains a devastating disease. The use of TKIs has been considered a mainstay of treatment for clear cell pathology, but other histologic subtypes such as papillary, chromophobe, and mixed subtypes, which is considered non-clear cell RCC, also make up a heterogeneous pattern and course of disease. This retrospective study characterizes renal cell carcinomas and their treatments.  Methods:  A retrospective chart review of the last 15 years was performed using data from a single-institution center at the George Washington University Cancer Center Tumor Registry Data. Statistical analysis was performed using the Fisher’s test, Chi-squared test, T-test, and Kaplan-Meier survival curves.  Results:  1043 patients with RCC were identified. Preliminary data analysis was performed on 92 of these patients. 48 had pure clear cell renal cell carcinoma (CCRCC) and 44 had non-clear cell carcinoma (NCC). Mean age of diagnosis was similar for both groups (58.25 years for CCRCC vs 62.14 years for NCC, p = 0.0977). However, hemoglobin levels at diagnosis were statistically significantly lower for CCRCC (p = 0.0261), as were calcium levels (p = 0.0187). All patients underwent surgical or local treatment. Only 2 patients received chemotherapy and 5 patients received molecularly targeted therapy. While not statistically significant, patients with CCRCC had surgery sooner after diagnosis than NCC (71 days vs 92 days), had longer time to metastatic disease (1033 days vs 820 days), and improved overall survival (1955 days vs 1446 days).  Conclusions:  NCC was a less favorable pathology than CCRCC with apparent later institution of surgical intervention as well as shorter time to metastatic disease and worse overall survival. Identifying patients with more aggressive disease earlier allows for the potential role for more aggressive therapies that may result in improved outcomes.