A consecutive 10-year series of 278 soft tissue sarcomas was prospectively graded, using a system based on the number of mitoses and taking into account parameters such as cellularity, anaplasia, necrosis, and histogenetic type and subtype of tumour. Prognostic factors in relation to metastasis-free survival were studied by uni- and multivariate analysis.
Fifty-seven (20·5 per cent) were low-grade tumours, 43 (15·5 per cent) were intermediate, and 178 (64 per cent) were high grade. High-grade tumours were divided into two groups; 80 (29 per cent) grade 3A (=5–20 mitoses per 10 high power fields (HPF)) and 78 grade 3B (28 per cent) (=more than 20 mitoses/10 HPF); 10 HPF corresponds to 2·5 mm2. Twenty (7·2 per cent) high-grade tumours could not be further subdivided.
Grading was found to be the prognostic factor associated with the strongest predictive value. Five-year survival in low-grade and intermediate tumours (95 and 86 per cent, respectively) differed significantly (P < 0·0001) from high grade (50 per cent) and (P = 0·0018) between grade 3A (64 per cent) and grade 3B (41 per cent). Other prognostic indicators of importance in high-grade tumours were age, local recurrence at presentation (primary operation outside the Centre), and localization (superficial vs. deep).