[Soft tissue sarcoma: histologic factors of prognosis]

With the intention of evaluating the prognostic value of 4 histopathological factors (cellularity polymorphism, mitotic index and necrosis), 80 cases of soft tissue sarcomas treated between 1960 and 1979 at the Oncology Institute of Montevideo, Uruguay were reviewed. There was a high correlation between the 4 variables. Their results provided similar models for actuarial survival rates and coefficients of regression. Nevertheless, when the factors were combined according to a linear regression model, cellularity lost almost all of its prognostic value, while necrosis and mitosis increased the prognostic influence of the equation. The percentage of variance explained by the combination of these factors was only 27 per cent. It is supposed that a substantial part of residual variance is due to factors which have not been included in the model, that is, the size of tumor, the depth of the lesion and its location. It is also conceivable that the intermediate number of cases and, more important, the heterogeneous distribution of histopathological types and primary sites might modify these results. Multiple prognostic evaluations are recommended for each histopathological type and for each different site.