Impact of Microvascular Invasion and Tumor Necrosis on the Prognosis of Korean Patients with pT1b Renal Cell Carcinoma

Objectives: To evaluate prognostic factors in pT1b renal cell carcinoma (RCC) patients for which no specific studies have been conducted on. Methods: The data of 270 patients diagnosed with pT1bN0M0 RCC at 2 institutions between January 1998 and June 2010 were retrospectively analyzed. Univariate and multivariate analyses using Cox proportional hazard models were used to identify pathologic and clinical factors that influenced prognosis. Five-year recurrence-free survival and cancer-specific survival were analyzed using the Kaplan- Meier method. Results: The median follow-up period was 55.5 months, and the mean patient age was 55.2 years (range: 2680). There were 12 cancer-related deaths, and tumor recurrence was noted in 22 patients between 8 and 120 months after surgery. Sites of metastases included the lung in 13 patients, bone in 5 patients, and other sites in 4 patients. Five-year recurrence-free survival and cancer-specific survival rates were 91.2 and 93.5%, respectively. Multivariate analyses revealed that the presence of microvascular invasion and tumor necrosis independently predicted prognosis. Conclusions: Microvascular invasion and tumor necrosis were found to be independent prognostic factors in pT1b RCC. This result will help urologists to provide patients with more accurate prognoses, and patients with confirmed microvascular invasion and tumor necrosis will require closer follow-up.