Clinical and flow cytometric analyses of renal cell carcinomas with reference to incidental or non-incidental detection.

: In recent years renal cell carcinomas have been diagnosed as incidental findings. The tumors are usually associated with low stage and good prognosis. To find out if they might have a different malignant potential from suspected tumors, we retrospectively compared 56 cases of incidentally detected tumors with 84 cases of suspected tumors, with regard to tumor stage, nuclear grade, tumor size and DNA ploidy pattern as evaluated by flow cytometry. The incidentally detected tumors were lower in stage (P < 0.01), smaller in size (P < 0.01) and higher in probability of survival (P < 0.02) than the suspected tumors, as other studies have reported. Meanwhile, there was no difference in nuclear grade, DNA ploidy pattern and survival in stage I tumors between the two groups of renal cancers. The results suggest that the better prognosis in incidental renal cancer might be due to early detection rather than lower malignant potential of this specific type of renal cancer.