Prognostic factors and survival according to tumour subtype in women presenting with breast cancer bone metastases at initial diagnosis: a SEER-based study

Table 2 Univariate analysis of prognostic factors

Characteristics	Median OS	P value	HR	95% CI for HR
Age at diagnosis		< 0.001
40–44 years	42		Reference
45–49 years	41		1.013	0.829–1.237
50–54 years	39		1.103	0.915–1.329
55–59 years	32		1.364	1.139–1.634
Race		< 0.001
White	41		Reference
Black	28		1.498	1.315–1.707
Other ^a	38		1.003	0.824–1.220
Marital status		< 0.001
Single	32		Reference
Married	42		0.723	0.638–0.819
Other ^b	35		0.903	0.772–1.057
Insurance		< 0.001
Uninsured	26		Reference
Insured	38		0.633	0.513–0.781
Grade		< 0.001
I	48		Reference
II	44		1.214	0.953–1.547
III or IV	28		2.071	1.634–2.625
Histology		0.003
Ductal	36		Reference
Lobular	44		0.748	0.624–0.897
Others	40		0.856	0.713–1.028
Laterality		0.084
Right	38		Reference
Left	38		1.058	0.949–1.179
Bilateral, single primary	13		2.254	1.008–5.039
Tumour subtype		< 0.001
HR+/HER2-	39		Reference
HR+/HER2+	52		0.747	0.640–0.873
HR−/HER2-	11		3.571	3.071–4.152
HR−/HER2+	35		1.132	0.917–1.397
Bone+Lung metastases		< 0.001
No	42		Reference
Yes	23		1.888	1.679–2.123
Bone+Liver metastases		< 0.001
No	44		Reference
Yes	22		2.182	1.950–2.443
Bone+Brain metastases		< 0.001
No	40		Reference
Yes	14		2.674	2.245–3.184
Only bone metastases		< 0.001
No	46		Reference
Yes	24		2.29	2.04–2.559
Surgery		< 0.001
No	32		Reference
Yes	52		0.496	0.433–0.568

ISSN: 1471-2407