Table 3. Median survival analyses of patients with high-grade osteosarcoma.

Factor	Patients	Events (Death)	Median survival, months	P-value
Age at diagnosis, years
≤15	46	28	17.7	0.428
>15	43	32	19.3
Gender
Male	50	40	18.1	0.067
Female	39	21	32.5
Enneking stage
IIB	45	20	62.3	<0.001
III	34	30	12.6
Site
Extremities	78	49	24.4	0.009
Axial	8	8	11.4
Tumor size
≤10 cm	59	36	24.4	0.171
>10 cm	18	13	12.8
Metastasis
At diagnosis	34	30	12.6	<0.001
At follow-up	21	13	20.9
No	24	7	Undefined
Chemoresistance
Good responders	8	3	Undefined	0.245
Poor responders	50	32	21.4
Histone deacetylase 1 expression
Low (Immunoreactive score≤1)	31	26	15.5	0.038
High (Immunoreactive score>1)	58	34	24.8
Histone deacetylase 2 expression
Low (Immunoreactive score≤10)	63	44	18.5	0.777
High (Immunoreactive score>10)	26	16	20.9
Histone deacetylase 3 expression
Low (Immunoreactive score≤6)	50	35	19.3	0.571
High (Immunoreactive score>6)	39	25	22.6
Histone deacetylases
Group1a: Not all low	71	44	22.6	0.016
Group2b: All low	18	16	10.7

P-values were calculated with the log-rank test, P-value<0.05 shown in bold.

^aGroup1—none or some histone deacetylase isoforms expressed at immunoreactive score lower than the cutoff.

^bGroup2—all-histone deacetylase isoforms expressed at immunoreactive score lower than the cutoff.