Objective: We performed a retrospective review of clinical T1a renal cell carcinoma patients treated in our institution. The clinicopathological findings and patients' prognoses were analyzed according to tumor size, and risk factors for tumor recurrence were elucidated.
Methods: A total of 140 cases of sporadic renal cell carcinoma with a diameter of 4 cm or less on computed tomography findings for preoperative evaluation were treated as clinical T1a. Patients underwent radical nephrectomy or nephron-sparing surgery, and were evaluated postoperatively every 3-6 months to screen for metastatic disease. Patients' medical records were reviewed retrospectively and the status of each patient was assessed.
Results: There were four cases of clinically metastatic disease at diagnosis. There were no correlations between tumor size and pathological stage, Fuhrman nuclear grade or histological type. The rate of cases with microvascular invasion on pathological findings increased according to tumor diameter. Disease recurrence occurred in six patients (5.7%) during a mean postoperative follow-up of 41.7 months. There was a significant difference in the recurrence-free rate between pT1a patients with a tumor diameter of 31 mm or more and other patient groups. In terms of microvascular invasion on histological findings, the probability of non-recurrence at 7 years was 0% for patients with and 92.9% for those without microvascular invasion.
Conclusions: Among T1a renal cell carcinoma, tumors over 30 mm in diameter may have aggressive biological potential, possibly due to microvascular invasion. Long-term follow-up is needed for these tumors.