Objective grading of prostate carcinoma based on fractal dimensions, "Beyond the Abstract," by P. Waliszewski, FEBU

BERKELEY, CA (UroToday.com) - Prostate cancer is known for its tremendous histological and biological variability. Hence, grading plays a pivotal role as a measure of biological aggressiveness of those malignant tumors. This measure is based on the subjective evaluation of tumor structure. The reduction of a variety of prostate carcinomas to a limited number of patterns of growth is undoubtedly a great achievement of the Gleason scoring system. However, prostate cancers may have very different dynamics of growth in spite of morphological similarity. Apparently, structure is not a perfect indicator of tumor evolution. Subjectivity is responsible for a tremendous inter- and intra-observer variability at the level of 40-80%, and leads to inaccuracy of the diagnostic algorithm and problems with patient stratification. Indeed, a great number of details in images of prostate carcinomas cannot be evaluated precisely by eye. In addition, the criteria of the original Gleason system have changed twice in 2005 and in 2010. So, it is impossible to compare results of classification and treatment before 2005 with those between 2005 and 2010, and after 2010.

Pathologists propose a central, hierarchical prostate pathology review as a remedy for the above problems. Certainly, both experience in the evaluation of histological images and expertise in the interpretation of the Gleason criteria may improve agreement in scoring, and reduce the variability. However, this central review cannot eliminate the subjectivity from the diagnostic algorithm. This goal can be achieved by the application of a quantitative approach based upon the objective computer-aided image analysis. Results of this study indicate that the complexity measures, such as the global fractal dimensions of the Rényi family can characterize complex images of prostate carcinomas with single numbers. In that way, one obtains the objectives measures of tumor complexity that can be analyzed by the common statistical techniques. According to the results of this study, the capacity fractal dimension D0 of the spatial distribution of cancer cell nuclei changes its values along with the self-affine changes in the spatial distribution of cancer cell nuclei during tumor progression, and is the most accurate measure of complexity. This feature can be applied to define classes of equivalence and classify prostate carcinomas in the objective way according to complexity of the spatial distribution of cancer cell nuclei. This novel approach is independent of the classification according to the Gleason system and requires the re-stratification of cases. This issue is discussed in detail in the article to be published in The Prostate.

In summary, one must emphasize that the novel approach is based exclusively on the traditional histological staining with hematoxylin and eosin. It requires the application of a camera and the sophisticated software for fractal analysis. We propose that the best way to go in order to standardize the approach would be a worldwide Internet portal, where any institute of pathology or urological clinic could load the images and analyze them using the identical software and conditions.

Written by:
P. Waliszewski, FEBU as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

Department of Urology, Justus-Liebig University, Giessen, Germany and Bedlewo Institute for Complexity Research, Poznan, Poland

Objective grading of prostate carcinoma based on fractal dimensions: Gleason 3 + 4 = 7a ≠ Gleason 4 + 3 = 7b - Abstract

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