ABSTRACT

Introduction:

Renal cell carcinoma (RCC), which accounts for 3% of all adult malignancies, is the most lethal carcinoma of the urologic cancers. The only effective curative treatment is radical surgery that is performed in an early stage. Tumor stage is the most important prognostic factor that consists of tumor size and invasion. Although anatomic structure and lesion volumes are useful for diagnosis and management decision but they are not practically appropriate as previous techniques. On the other hand, Cavalieri principle is much easier in practice and often takes less time on summing. High accuracy rates are obtained in volume measurement with lesions of complex shape. The aim of this study was to investigate the use of stereological method for estimation of RCC volume on computed tomography images and compare these volumes with the tumor stage.

Material and method:

The study involved 51 patients with renal cell carcinoma (RCC) who underwent to radical nephrectomy in our clinic. The patients were evaluated by intravenous pyelography (IVP), color Doppler duplex ultrasonography and computed tomography. Slice thickness were 10 mm on every section. A square grid test system with d=0.4, 0.15 and 0.15 cm between test points i.e. 0.16, 0.0225 and 0.0225 cm2 representing area per point were used to estimate the sectioned surface area. The representing area per point in the grid was corrected with the reduction ratio of printed sections. The volume of the entire RCC was estimated by the formula of Cavalierie's principles. Clinical staging was performed according to 1997 TNM classification.

Results:

The study involved 51 patients, of these 35 (68.6%) were male and 16 were (31.4%) female. 23 patients were in stage T1 (45.1%), 12 were in stage T2 (23.5%), 16 were in stage T3 (31.4%). Estimated tumor volume on stage T1 was 125.52±102.18 cm3, on stage T2 346.25±112.55 cm3 on stage T3 694.88 ±405.46 cm3. When we compared the volume ratios between the stages, the differences were statistically significant between stage T1 and T2 (p<0.001) and between stage T2 and T3 (p<0.001). We found minimum 8.69% and maximum 97.15% mean value for volume ratios. On stage T1 mean volume ratio was 28.44%±14.37% on stage T2 55.42±12.43% and on stage T3 72.48±17.15%. There were obvious difference among the groups but these were not statistically significant (p>0.05).

Conclusion:

These volume estimation methods have been thoroughly studied on CT scans of complex model systems. We can estimate renal tumor volume by using Cavalieri's principle on CT sections. This method is inexpensive, safe and rapid, since point counting is carried out within a couple of minutes per RCC.

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