Tumor doubling time of renal cell carcinoma measured by CT.

Introduction: Increasing numbers of patients are now being incidentally detected with small-sized renal cell carcinoma (RCC). The natural history of small renal masses is not completely understood. Currently, there are no specific tumor markers to determine initial risk or progression to metastatic disease. Growth rate and tumor size are factors shown to be predictive of tumor biology. In this study, we attempted to examine the natural history of RCC and calculated the doubling times (DTs) of untreated RCC at the primary site.

Materials And Methods: We retrospectively reviewed the records of all patients with RCC who had at least two measurements of the same tumor mass obtained on computed tomography (CT) imaging on two different dates (at least 6 months apart) during periods of non-treatment. The tumor volume was calculated at two points in time using images yielded by the CT imaging. The tumor DT was calculated using the following equation: DT = (T - T0) × log2/logV - logV0.

Results: Twenty-two (13 male and nine female) patients with ages ranging from 32 to 71 years (mean 52.22 years) were included in the study. The initial maximum tumor diameter ranged from 2.8 to 6.8 cm (mean 3.93 cm) and the last maximum tumor diameter ranged from 3.2 to 7.8 cm (mean 4.39 cm). The DT for the entire population was 460.01 days (range 174-913 days).

Conclusions: RCC is a diverse disease process, with the majority of lesions demonstrating malignant disorder. In our study, the DT for the patient population was 460.01 days (range 174-913 days).