Problems in grading soft tissue sarcomas.

Clinicians, particularly medical oncologists, place increasing importance on histologic grading as a means of informing their treatment decisions in patients with soft tissue sarcoma. Numerous different grading systems (with a variable number of grades) have been described. Although these have often used different parameters, it is nevertheless generally accepted that histologic grade, however derived, is probably the best prognostic indicator in these sarcoma patients. Unfortunately, however, there is no consensus as to the best grading system, and even those schemes that are most widely applied (those of the French National Cancer Centers and the National Cancer Institute in the United States) have important and acknowledged limitations. Furthermore, assessment of many of the most popular grading parameters is necessarily subjective, and, to date, potentially more objective measures of proliferative activity and ploidy (eg, using immunohistochemistry or DNA flow cytometry) have not improved on experienced morphologic grading. In addition, the confounding (and often misleading) effect on histologic grade of preoperative therapy, which is increasingly used, has not been addressed in any meaningful way. This overview highlights the limitations, problems, and concerns regarding histologic grading of soft tissue sarcomas.