Prognostic significance of argyrophilic nucleolar organizer staining in soft‐tissue sarcomas

The utility of argyrophilic stain for nucleolar organizer region (AgNOR) for estimating proliferative activity and prognosis of soft-tissue sarcomas (STS) was examined. Formalin-fixed and paraffin-embedded sections of 38 cases with STS were used; the reaction product of AgNOR stain was observed as dots mainly in the nucleoli. The mean number of AgNOR dots per nucleus of tumor cells was calculated in 200 cells (AgNOR count). The AgNOR count, ranging from 1.4 to 16.1 (mean, 7.5), showed a good correlation with cellularity (r = 0.483, p less than 0.003) and histologic grade (r = 0.626, p less than 0.00005), but less shown with mitotic counts (r = 0.350, p less than 0.04). The prognosis of cases with AgNOR low-count group (5-year survival rate was 74.6%) was much better than those in high count group (33.3%) (p less than 0.0005). The AgNOR count correlated well with reactivity of tumor cells for Ki-67 staining, which was available only in freshly prepared sections. These findings suggested that the AgNOR staining is a simple and useful method for estimating tumor-cell proliferation and prognosis of patients with STS.