Table 5.

Subgroup survival analysis for patients with different histo-types of undifferentiated chondrosarcoma in the SEER database.

Histo-type	Variable	Univariate analysis (log-rank test)		Multivariate analysis (Cox regression)		Univariate analysis (log-rank test)		Multivariate analysis (Cox regression)
		5-year OS	P	HR (95% CI)	P	5-year CSS	P	HR (95% CI)	P
Chondrosarco-ma, NOS	Radiotherapy		0.642				0.709
	Performed	27.8%				32.0%
	Not performed	31.0%				37.1%
	Treatment		0.064				0.085
	Both	27.9%				40.8%
	Surgery only	34.9%				39.1%
	Radiotherapy only	1.0%				1.4%
	None	8.0%				11.5%
Myxoid	Radiotherapy		0.608				0.211
	Performed	42.7%				52.9%
	Not performed	28.6%				28.6%
	Treatment		0.000				0.000
	Both	45.6%				58.0%
	Surgery only	30.8%				30.8%
	Radiotherapy only	NA*				NA*
	None	NA*				NA*
Mesenchymal	Radiotherapy		0.934				0.883
	Performed	53.7%				59.7%
	Not performed	56.7%				60.2%
	Treatment		0.703				0.380
	Both	60.9%				69.6%
	Surgery only	61.4%				65.1%
	Radiotherapy only	1.0%				1.0%
	None	33.3%				33.3%
Dedifferentiated	Radiotherapy		0.020				0.005
	Performed	50.2%		Reference		58.3%		Reference
	Not performed	20.6%		2.64 (1.17–5.95)	0.019	21.5%		3.56 (1.39–9.15)	0.008
	Treatment		0.015	NA#			0.007	NA#
	Both	53.3%				61.9%
	Surgery only	23.6%				24.3%
	Radiotherapy only	NA*				NA*
	None	NA*				NA*

SEER – Surveillance, Epidemiology, and End Results; OS – overall survival; CSS – cancer-specific survival; HR – hazard ratio; CI – confidence interval; NOS – not otherwise specified;

NA^* – the analysis is not available because of the small sample size;

NA^# – the analysis is not available because of the covariance.