Clinical Epidemiology of Low-Grade and Dedifferentiated Osteosarcoma in Norway during 1975 and 2009
Table 1
Clinicopathological variables in 54 low-grade and dedifferentiated osteosarcoma (OS) patients.
Low-grade OS (%)
Dedifferentiated OS (%)
All patients (%)
All patients
42
12
54
Gender
Male
23 (55)
5 (42)
28 (52)
Female
19 (45)
7 (58)
26 (48)
Histological subgroups
Parosteal OS
12 (29)
8 (67)
20 (37)
Low-grade central OS
25 (60)
4 (33)
29 (54)
Secondary low-grade OS
4 (10)
4 (7)
Extraskeletal low-grade OS
1 (2)
1 (2)
Tumour size
≤6 cm
20 (67)
2 (25)
22 (58)
>6 cm
10 (33)
6 (75)
16 (42)
Median/mean size in cm
6/6
11/12
6/7
Range in cm
1–15
5–30
1–30
Symptom length
≤6 months
16 (48)
5 (56)
21 (50)
>6 months
17 (52)
4 (44)
21 (50)
Median/mean length in months
7/18
6/27
7/20
Range in months
1–108
4–120
1–120
No dedifferentiation at diagnosis or during follow-up. Missing values equal the difference between the summarized number from each subgroup in the fourth column and the total number of patients in the study.
