Long-term treatment outcomes of patients with non-clear cell renal cell carcinoma

Objective: to analyze factors affecting relapse-free and overall survival of patients with non-metastatic non-clear cell renal cell carcinoma (nccRCC) after surgical treatment.

Materials and methods. This study included 279 (13.62 %) nccRCC patients from the database containing information on 2049 patients with localized and locally advanced renal cell carcinoma (RCC) without distant metastases who underwent surgical treatment in the Department of Urologic Oncology, P.A. Herzen Moscow Oncology Research Institute between 2002 and 2018. Gender ratio was 1.36:1 (161 men (57.7 %) and 118 women (42.3 %)). Median follow-up time was 34.5 months (range: 1-141 months). Patients had undergone either radical nephrectomy (n = 117; 41.9 %) or kidney resection (n = 160; 57.4 %) or radiofrequency thermal ablation (n = 2; 0.7 %). Standard (open) transperitoneal approach was used in 135 patients (48.4 %) patients, whereas 144 (51.6 %) patients were operated on via laparoscopic approach. Postoperative histological examination demonstrated that 110 participants (39.4 %) had chromophobe RCC, while 79 (28.3 %) and 63 (22.6 %) individuals had type 1 and type 2 papillary RCC, respectively. Twenty-seven patients were found to have rare or mixed variants of nccRCC (they were excluded from the analysis due to their relatively small number). Patients were diagnosed with the following stages of cancer: рТ1а (n = 129; 46.2 %), pT1b (n = 72; 25.8 %), рТ2а (n = 18; 6.5 %), pT2b (n = 8; 2.9 %), рТ3а (n = 31; 11.1 %), pT3b (n = 4; 1.4 %), рТ4 (n = 1; 0,4 %), and pN+ (n = 16; 5.7 %).

Results and conclusion. 13 patients (4.7 %) were diagnosed progressive disease; 9 patients (3.2 %) died due to nccRCC progression. The highest relapse-free and overall survival rates were registered in the patients with type 1 papillary RCC and chromophobe RCC.

Spearman's correlation analysis showed a significant correlation between the risk of disease progression and tumor size (R = 0.23; p <0.0001), pT stage (R = 0.24; p = 0.0001), vascular invasion (R = 0.36; p <0.0001), pN+ stage (R = 0.4; p <0.0001), surgical resection margin (R = 0.5; p <0.0001), histological variant (R = 0.14; p = 0.02), and Furman differentiation grade (R = 0.16; p = 0.02). The following factors were found to have an impact on relapse-free survival according to multivariate Cox regression: presence of necrosis (p = 0.04), pT stage (p = 0.03), and vascular invasion (p = 0.08), although the last variable failed to reach statistical significance. Cancer-specific survival was significantly affected by pT stage (p = 0.01) and Furman differentiation grade (p = 0.04). None of the factors demonstrated significant associations with overall survival. Thus, the most significant prognostic factor affecting relapse-free, overall, and cancer-specific survival in nccRCC patients was the pT stage (p <0.05).