Natural history of malignant bone disease in breast cancer and the use of cumulative mean functions to measure skeletal morbidity

Table 4 Full multivariate analysis for overall survival

Variable	RR	(95% CI)	pvalue
Age ≥ 50 years	1.18	(0.78, 1.78)	0.434
ECOG performance status
2 – 3 versus 0 – 1	1.15	(0.76, 1.76)	0.507
Hydroxyproline/creatinine ratio (centered)	1.06	(1.02, 1.10)	0.001
Bone-specific alkaline phosphatase (U/L)	1.00	(0.99, 1.01)	0.471
Estrogen-receptor status versus negative
Positive	0.78	(0.44, 1.40)	0.406
Unknown	1.53	(0.67, 3.50)	0.314
Progesterone-receptor status versus negative
Positive	0.58	(0.33, 1.00)	0.050
Unknown	0.51	(0.24, 1.07)	0.074
Sites of metastasis (yes versus no)
Bone as only metastatic site	0.75	(0.44, 1.29)	0.301
Lung	1.49	(0.733, 3.01)	0.273
Liver	0.84	(0.435, 1.61)	0.593
Time from diagnosis of bone metastases to study entry, years	1.21	(1.05, 1.38)	0.008
Time from cancer diagnosis to study entry, years	0.83	(0.72, 0.95)	0.008
Lesion characteristics and numbers
≥ 3 osteolytic versus < 3 osteolytic	1.34	(0.92, 1.95)	0.128
1 – 2 osteoblastic versus no osteoblastic	1.19	(0.74, 1.92)	0.471
≥ 3 osteoblastic versus no osteoblastic	0.79	(0.36, 1.74)	0.559
1 – 2 mixed versus no mixed	0.64	(0.36, 1.16)	0.140
≥ 3 mixed versus no mixed	0.63	(0.35, 1.12)	0.112
Prior fracture (yes versus no)	0.99	(0.58, 1.67)	0.964
Pain scores (centered)	1.03	(0.96, 1.11)	0.406
Prior chemotherapy (yes versus no)	1.54	(0.46, 5.16)	0.484
≥ 2 prior hormonal therapies (yes versus no)	1.61	(1.08, 2.40)	0.020
Prior radiotherapy (yes versus no)	0.75	(0.47, 1.20)	0.230

Values in bold represent statistically significant correlations.
RR = Relative risk, CI = Confidence interval, ECOG = Eastern Cooperative Oncology Group, U = Units.

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