Introduction

To evaluate postoperative outcome of cystic renal cell carcinoma (RCC) defined on preoperative computed tomography (CT), and to find the optimal cut-off of cystic cystic proportion in association with patients’ prognosis.

Methods

In this institutional review board-approved study with waiver of informed consent, a total of 1315 patients who received surgery for single RCC with pre-operative CT were enrolled. The cystic proportion of RCC was determined on CT. The optimal cut-off of cystic proportion was explored regarding cancer-specific survival. The RCCs were categorized as cystic or non-cystic RCCs according to conventional (i.e. cystic proportion ? 75%) and the optimal cut-off, and then post-operative outcomes were compared between the two groups. Multivariate Cox regression analysis was performed to determine the independent predictor for cancer-specific survival.

Results

Of the 1315 lesions, 107 (8.1%) were identified as cystic RCCs according to a conventional cut-off. Postoperative outcome of cystic RCC was significantly better than that of non-cystic RCC (P<0.001). Neither metastasis nor recurrence in patients with cystic RCC was developed after surgery. In association with cancer-specific survival rate, the optimal cut-off of cystic proportion was 45%, and 197 (15.0%) were defined as cystic RCCs accordingly. On Cox regression analysis, cystic proportion ? 45% in RCC was an independent predictor of favorable outcome regarding cancer-specific survival (hazard ratio 0.34, P = 0.03).

Conclusions

Cystic RCC defined on preoperative CT is associated with low metastatic potential and favorable outcomes after surgery. Particularly, cystic proportion ? 45% is an independent prognostic factor for favorable survival.

Funding

none