Pseudocapsule thickness is positively associated with prognosis in patients with clear cell renal cell carcinoma

Background Tumour pseudocapsule shows plasticity, whose representative indicator- pseudocapsule thickness- was little studied in clear cell renal cell carcinoma (ccRCC). Methods We enrolled 1037 ccRCC patients who underwent surgery between 2006 and 2013 at our institution. The patients did not receive therapy before surgery and were confirmed to have a pathological pseudocapsule. The associations of pseudocapsule thickness with overall survival and disease-free survival were studied using multivariable Cox regression analyses. Patients were stratified using points of maximum separation. Influential factors were examined with logistic regression. Results The average thickness was 0.47 mm (median: 0.43, interquartile range: 0.28-0.6). The average follow-up was 92.1. In multivariable analyses, every 0.1-mm increase in thickness resulted in a decreased risk of death (hazard ratio (HR) 0.906, p = 0.011) but not recurrence (HR 0.948, p = 0.105). For patients with a pseudocapsule thickness of 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm and 1.0 mm, the estimated 10-year overall survival rates were 74.9%, 83.3%, 87.8%, 90.1% and 91.0%, and the 10-year disease-free survival rates were 69.6%, 76.6%, 80.8%, 83.1% and 84.1%, respectively, with the best cut-off value being approximately 0.37 mm. The results of logistic regression revealed that female sex (p < 0.001), age (p = 0.002), a higher neutrophil count (p = 0.011), large tumour size (p < 0.001) and necrosis (p = 0.011) were independently associated with a thin pseudocapsule (<= 0.37 mm). Conclusions Pseudocapsule thickness is heterogeneous in clear cell renal cell carcinoma. Generally, increased thickness is associated with improvement in long-term survival. A pseudocapsule being 0.37 mm or thinner is mostly influenced by both systematic and tumor-related parameters.