[Vertical tumor thickness as an estimate of actual tumor volume]

According to Cavalieri, the volume of any body-irrespective of its shape-can easily be estimated on the basis of the area of slabs of known thickness. We made use of this old principle in order to determine the correlation between the volume of skin tumors and their maximal vertical thickness. Investigations of a total of 30 benign and malignant tumors of the skin of various shapes showed a correlation coefficient of r = 0.77. Therefore, the widely used determination of the vertical thickness of malignant melanomas can be regarded as a good estimator of the tumor volume and seems to be appropriate for histological tumor staging. Together with high frequency ultrasound, Cavalieri's method allows a simple and rapid pretherapeutical in-vivo determination of the tumor volume. However, only prospective studies can reveal whether the determination of the tumor volume is of superior prognostic significance to the established techniques.