Although the percentage of patients with renal cell carcinoma (RCC) extending into venous systems is unexpectedly high, the prognostic impact and independency of venous tumor thrombus-related factors on overall survival (OS) remain controversial. Furthermore, the prognostic impact of various clinicopathologic factors including tumor thrombus-related factors on OS may change with elapsed years after the intervention and also with follow-up duration of participants. The aim of the study is to explore independent and universal predictive preoperative and intraoperative clinicopathologic factors on OS in patients with RCC extending into venous systems using subgroup analysis in terms of restricted follow-up duration and yearly-based survivors.
Between 1980 and 2009, 292 patients diagnosed with RCC with venous tumor thrombus were retrospectively registered for this study. The prognostic impacts of various clinicopathologic and surgical treatment factors including levels of venous thrombus, venous wall invasion status and likelihood of aggressive cytoreductive operation, were investigated using Kaplan-Meier method and following multivariate Cox proportional hazards model for all patients and those still alive at 1, 2, and 3 years of follow-up. To investigate the impact of follow-up duration on the statistical analyses, multivariate logistic regression analyses were used to explore prognostic factors using restricted data until 1, 2, and 3 years of follow-up.
The median follow-up duration was 40.4 months. The 5-year OS was 47.6%. Several independent predictive factors were identified in each subgroup analysis in terms of yearly-based survival and restricted follow-up duration. The presence of tumor thrombus invading to venous wall was independently related to OS in the full-range follow-up data and in survivors at 2 and 3 years of follow-up. Using restricted follow-up data until 1, 2, and 3 years of follow-up, many independent predictive factors changed with follow-up duration, but surgical category could be universal and independent predictive factors.
The most universal factors affecting improvement both in short-term and long-term survivals could be cytoreductive surgery and absence of venous wall invasion. It may mean that feasible aggressive cytoreductive operation following more reliable preoperative imaging for predicting venous wall invasion status would improve OS for patients with RCC extending into venous systems.