Histologic grading in soft-tissue sarcomas. An analysis of 194 cases including AgNOR count and mast-cell count

In order to establish a new histologic grading system for STS, we evaluated histologic prognostic factors. For this purpose, we selected 194 patients with STS: 31 in the upper extremities, 63 in the trunk, and 100 in lower extremities. All the patients were treated by surgery, followed by chemotherapy in 74 cases, radiotherapy in 11, chemotherapy and radiotherapy in 30, or no adjuvant treatment in 79. Histologic factors evaluated were mitotic count, extent of necrosis, cellularity, cellular pleomorphism, extent of myxoid change, sclerosis, non-specific histologic diagnosis, counting of reaction product in silver stain for nucleolar organizer regions (AgNOR) and mast-cell counts. Univariate analysis revealed mitotic count, necrosis, cellularity, cellular pleomorphism, non-specific histologic classification, AgNOR count and mast-cell count to be significantly related to prognosis. Multivariate analysis revealed that AgNOR count, cellularity and necrosis were independent prognostic factors. A new grading system was introduced: low-grade, intermediate-grade and high-grade. The survival between each group were significantly different; the 5-year-survival rate in patients of the low-, intermediate- and high-grade groups was 87%, 74% and 35% respectively. Our findings suggest that this histologic grading system may be useful for making therapeutic decisions.