Table 4. Multivariate analysis of age on CSS in MTC according to clinicopathological variables.

	Multivariate Analysis
Variable per age subgroup	HR (95% CI)	P value
Sex1
Male
≤ 49 years	1 (Reference)
50–69 years	1.079 (0.497–2.342)	0.847
≥ 70 years	1.738 (0.656–4.608)	0.267
Female
≤ 49 years	1 (Reference)
50–69 years	1.853 (1.363–2.004)	0.015
≥ 70 years	2.992 (1.109–8.076)	0.030
Race2
African American
≤ 49 years	1 (Reference)
50–69 years	1.545 (0.350–6.823)	0.566
≥ 70 years	None	0.989
Non-Hispanic white
≤ 49 years	1 (Reference)
50–69 years	1.722 (1.483–1.912)	0.046
≥ 70 years	2.208 (1.062–4.592)	0.034
TNM stage3
Stage I
≤ 49 years	1 (Reference)
50–69 years	None	0.978
≥ 70 years	None	0.990
Stage II
≤ 49 years	1 (Reference)
50–69 years	0.190 (0.022–1.644)	0.131
≥ 70 years	None	0.990
Stage III
≤ 49 years	1 (Reference)
50–69 years	None	0.966
≥ 70 years	None	0.962
Stage IV
≤ 49 years	1 (Reference)
50–69 years	1.697 (1.387–3.660)	0.018
≥ 70 years	3.763 (1.565–9.050)	0.003

¹P-value for HR was adjusted for race and TNM stage as covariates.

²P-value for HR was adjusted for sex and TNM stage as covariates.

³P-value for HR was adjusted for sex and age as covariates.

None refers to lack of results because of analysis incapability.

Abbreviations: MTC, medullary thyroid cancer; CSS, cancer-specific survival; HR, hazard ratio; CI, confidence interval; TNM, tumor type, lymph node involvement, distant metastasis.