Characteristics of aggressive variants in T1a renal cell carcinoma

To explore factors associated with metastasis and prognosis in T1a renal cell carcinoma (RCC). We retrospectively reviewed 451 cases of sporadic T1aRCC among 1,060 patients admitted to the Department of Urology at Hamamatsu University Hospital and affiliated hospitals between 1978 and 2007. Clinicopathological factors were analyzed for metastatic and prognostic risks. We identified 32 RCC patients with metastatic disease, 22 with synchronous and 10 with metachronous metastatic RCC. Patients with metastatic disease had a significantly higher incidence of symptomatic cancer, as well as greater tumor size, C-reactive protein (CRP) level, sarcomatoid component ratio, histological grade 3 and microvascular invasion than those without metastasis. Among the 32 patients with metastasis, there is no significant difference in clinicopathological factors. The most common site of metastasis was bone. Among patients with metastatic T1aRCC, findings at diagnosis of a symptomatic cancer, CRP level of 0.4 mg/dL or more, tumor size of 3.0 cm or greater, histological grade 3, a sarcomatoid component and microvascular invasion appeared to be significant and independent risk factors. Significant independent risk factors with metachronous metastatic RCC were a symptomatic cancer and a sarcomatoid component at diagnosis. A CRP level of 0.4 mg/dL or more was also an independent prognostic factor for overall survival. RCC patients with findings at diagnosis of a symptomatic cancer, a sarcomatoid component and CRP level of 0.4 mg/dL or more require intensive follow-up.