Growth rates of primary and metastatic lesions of renal cell carcinoma

Background: The natural history and growth rate of renal cell carcinoma (RC C) have not yet been determined. The growth rates of primary lesions in inc identally found RCC were compared with those of metastatic lesions. Methods: Sixteen patients who did not receive immediate surgical treatment for renal solid masses that were later proven to be RCC were reviewed retro spectively. All primary lesions of the 16 patients were found incidentally. For comparison, metastatic lesions were evaluated in another 16 patients w ith RCC. Of these, 11 underwent surgical treatment for the primary lesions. Results: The growth rates of primary and metastatic lesions of RCC varied. They ranged from 0.10 to 1.35 cm/year for primary lesions and from 0.08 to 7.87cm/year for metastatic lesions. The growth rate of primary lesions of i ncidentally found RCC was lower than that of metastatic lesions (P=0.0159). The initial tumor diameter and pathological grade did not affect the growt h rate of the primary lesion of incidentally found RCC. However, a close co rrelation was found between the growth rate of metastatic lesions and the p athological grade of the primary lesion in patients with metastasis. Conclusions: The growth rate of incidentally found RCC varied. Some patient s with the disease may be candidates for 'watchful waiting' when an immedia te surgical treatment is not indicated, but they should be selected with gr eat caution.