All I II III IV I-II I-III III-IV Large size Deep location High grade 490 27 67 124 272 94 218 396 RR 2.4 1.3 2.5 0.71 1.0 0.97 0.79 0.57 0.98 0.87 0.64 size 7.6 10.1 95% CI 0.75–0.67 1.0–0.93 0.87–0.72 0.63–0.51 1.0–0.95 0.90–0.85 0.69–0.59 Table 2: Mean size (cm) and depth (n = 490) Size category 1–5 cm >5 cm size range number range number Superficial Deep 2.9 2.8 (1–5) (1–5) 87 78 (6–28) (6–30) 82 243 Table 3: Prognostic factors, multivariate analysis (n = 490) High grade=III-IV High grade=IV 95% CI 1.5–3.7 0.86–1.8 1.6–3.7 RR 2.6 1.4 15 95% CI 1.7–4.0 0.96–2.0 4.8–47 series nor when separately analyzed in MFH, leiomyosar- coma, liposarcoma, synovial sarcoma, and the remaining histotypes as one group (data not shown). Prognosis related to combinations of depth, size and grade (Tables 4,5, Figure 1) The survival rate for small and low (I-II or I-III) grade tumors was similar whether the tumor was superficial or deep. Likewise, the survival rate for small and high (III-IV or IV) grade tumors was similar whether the tumor was superficial or deep. However, for large and high grade tumors the survival rate was lower for deep than superfi- cial tumors. These observations were the same irrespective of how grade was dichotomized. Prognosis based on only grade and size (Tables 6,7) After finding that depth had no major prognostic value we assessed staging based on only grade (low, high (III-IV or BMC Cancer 2003, 3 http://www.biomedcentral.com/1471-2407/3/17 Table 1: Survival according to histologic grade. Grade(s) No. of patients Survival Figure 1 Venn diagram showing approximate 5-yr metastasis-free sur- vival rates in the 8 combinations of depth, size and grade (high=III-IV). For exact survival rates see Table 4. Green fields include the four subsets of low grade tumors. The sur- vival rates are between 1 and 0.9 irrespective of depth and size. Blue fields include the two subsets of small high grade tumors, both with survival rates of 0.8. Red fields include the two subsets of large and high grade tumors. The survival rates differ, being 0.7 for superficial tumors and 0,5 for deep tumors. The explanation is that the mean size of deep- seated, large tumors is greater than that of superficial, large tumors, see Table 2. The principal findings are the same when high grade is defined as grade IV, see Table 5. IV)) and size. We categorized size in 3 groups, 1–5 cm, 6– 10 cm, and larger than 10 cm. We found that a 4 tiered staging system led to decreasing survival with increasing stage with good separation of the survival rate between the stages. We made the same observations irrespective of how grade was dichotomized. Discussion Many staging systems for soft tissue sarcomas of the extremity and trunk wall have been proposed but none is generally accepted. One reason may be that it is impossible to create a system common for all entities of soft tissue sarcoma since prognostic factors vary regarding Page 3 of 5 (page number not for citation purposes)