It cannot be described adequately by classic Euclidean geometry, but may be estimated by the determination of the fractal dimension. There is increasing use of fractal geometry for medical signal analysis with applications to pattern recognition, texture analysis and segmentation. This analysis has also been applied for the study of cell nuclei,Semaxanib as the fractal nature of chromatin and its surrounding nucleoplasmic space has been demonstrated by different methods. Moreover, the fractal characteristics of nuclear chromatin measured in cytological or histological preparations have shown to be of prognostic importance in several neoplasias. Therefore we investigated whether the fractal dimension of nuclear chromatin measured in routinely stained cytological smears of myeloma patients has a relation to the survival of the patients. Finally, the prognostic relevance of all these parameters was analyzed in univariate and multivariate Cox regressions. The stability of the Cox model was tested by bootstrap resampling. This is a useful Evofosfamide procedure to test the internal stability of a model proposed. It consists of creating new data sets of equal size by random sampling of the original data with replacement. In an individual new bootstrap sample, a patient may be represented once, multiple times or not at all. A new Cox regression was then calculated for each of these new data sets in order to obtain the bootstrap parameter estimates. This procedure is very useful in order to point out the most important variables. The median age of our patients at diagnosis was years, which is considerably lower than that reported in studies. A younger age of the patients at diagnosis, when compared with other countries, has also been reported for other hematological neoplasias in Brazil, such as myelodysplastic syndromes and myeloid leukemias. Besides a recent epidemiological survey of patients with multiple myeloma in our country showed a similar mean age and also a high frequency of advanced ISS. No final conclusive explanation has been found for this phenomenon.