Prognostic value of tumor-stroma ratio in clear cell renal cell carcinoma after surgery.

Background: Clear cell renal cell carcinoma (ccRCC) is one of the most common urological tumors, and its incidence is increasing year by year. Tumor stroma ratio (TSR) can reflect the amount of stromal component around tumor cells, and can independently predict the prognosis of tumor. This study aims to evaluate the prognostic value of TSR in ccRCC patients.

Methods: From January 2010 to December 2015, clinical and histopathological data of patients with ccRCC patients who underwent surgical operation were collected. Using TSR (50%) as the cut-off value, the patients were divided into low-TSR group (<50%) and high-TSR group (≥50%). The clinicopathological characteristics and survival status of patients were compared between the two groups. Univariate and multivariate analyses were used to identify the prognostic factors for overall survival (OS), cancer-specific survival (CSS), metastasis-free survival (MFS).

Results: The mean age of 569 patients was 56.84±12.76 years old. There were 401 males and 168 females. According to the TSR, patients were divided into low-TSR group (n=333, 58.5%) and high-TSR group (n=236, 41.5%). The median follow-up time was 67.0 months (interquartile range, 33.0-72.0 months). The 5-year OS, CSS and MFS were 91.2%, 94.6% and 91.0%, respectively. The 5-year OS, CSS and MFS were 84.2%,89.7% and 82.7% in the high-TSR group and 96.1%, 98.0% and 96.0% in the low-TSR group (P<0.05). Multivariate analysis showed that age >60 years [hazard ratio (HR) =2.455, 95% confidence interval (CI): 1.292-4.668, P=0.006), tumor grade (HR =6.580, 95% CI: 3.276-13.216, P<0.001) and TSR (HR =2.611, 95% CI: 1.265-5.387, P=0.009) were independent prognostic factors for OS. Multivariate analysis showed that tumor stage (HR =3.213, 95% CI: 1.437-7.184, P=0.004), tumor grade (HR =6.102, 95% CI: 2.664-13.976, P<0.001) and TSR (HR =2.653, 95% CI: 1.063-6.621, P=0.03) were independent prognostic factors for CSS. Multivariate analysis showed that tumor stage (HR =4.805, 95% CI: 2.677-8.624, P<0.001), tumor grade (HR =6.423, 95% CI: 3.432-12.020, P<0.001), hemorrhage (HR =0.514, 95% CI: 0.265-0.996, P=0.049) and TSR (HR =2.370, 95% CI: 1.264-4.443, P=0.007) were independent prognostic factors for MFS.

Conclusions: TSR is a new independent prognostic risk factor for ccRCC patients. The assessment of TSR is simple and cost-effective, and it is a useful supplement added to the pathological evaluation system.