Clinical Epidemiology of Low-Grade and Dedifferentiated Osteosarcoma in Norway during 1975 and 2009
Table 5
Univariate Kaplan-Meier analyses of five-year sarcoma-specific survival and event-free survival according to different characteristics of 54 patients with low-grade or dedifferentiated osteosarcoma (OS).
Sarcoma-specific survival
Event-free survival
Patients (%)
5 years in % (95% CI in %)
Patients (%)
5 years in % (95% CI in %)
Primary site of tumour
0.287
0.844
Extremity
33 (61)
91 (74–97)
30 (59)
80 (61–91)
Axial
21 (39)
90 (74–96)
21 (41)
65 (41–82)
Age
0.158
0.063
≤40 years
33 (61)
94 (77–98)
32 (63)
81 (62–91)
>40 years
21 (39)
86 (62–95)
19 (37)
63 (37–80)
Malignancy grade
<0.001
0.004
Low-grade
42 (78)
93 (79–98)
41 (80)
80 (64–90)
Dedifferentiated
12 (22)
83 (48–96)
10 (20)
50 (18–75)
Subgroup of OS
0.738
0.868
Parosteal OS
20 (37)
90 (66–97)
18 (35)
72 (46–87)
Low-grade central OS
29 (54)
93 (75–98)
28 (55)
75 (55–87)
Other
5 (9)
75 (13–96)
5 (10)
75 (13–96)
Local recurrence
0.010
<0.001
No
40 (74)
92 (78–97)
37 (73)
97 (82–97)
Yes
14 (26)
86 (54–96)
14 (27)
20 (5–42)
Metastases at diagnosis or during follow-up
<0.001
0.001
No
44 (81)
95 (83–99)
44 (86)
79 (64–88)
Yes
10 (19)
70 (33–89)
7 (14)
57 (17–84)
Surgery
<0.001
<0.001
Free margin
43 (83)
98 (83–100)
42 (86)
83 (52–95)
Positive margin
9 (17)
56 (20–81)
7 (14)
29 (4–62)
Adequate chemotherapy
0.091
0.447
No
45 (83)
93 (80–98)
44 (86)
74 (58–85)
Yes
9 (17)
78 (36–94)
7 (14)
71 (26–92)
Radiotherapy
0.003
0.106
No
48 (89)
94 (82–98)
45 (88)
77 (62–87)
Yes
6 (11)
67 (20–90)
6 (12)
50 (11–80)
Confidence interval. Log-rank test. Surgical margins after resection of primary tumour, last surgery performed. Curative treatment intent.
