Grading sarcomas: histologic and molecular approaches

Histological grading, that is, grading based only on histological parameters, evaluates the degree of malignancy and the probability of distant metastasis for cancer. Several grading systems have been reported for sarcomas but the two most widely-used systems are the National Cancer Institute and the French systems. Histological grade is recognized as the most important prognostic factor for soft tissue sarcomas. However, this approach presents several limitations such as moderate reproducibility, existence of an intermediate grade and the current nearly universal use of core needle biopsies. A molecular grading system which significantly outperforms histological grading has been recently described for sarcomas. It is based on the expression profile of 67 genes related to chromosome complexity and mitosis management (CINSARC for Complexity INdex in SARComas). In this article we discuss both approaches as well as the future of grading, regarding the respective values of histological and molecular grading systems, validation, extension, refinement and practical use of the molecular grading.