Effect of Central Nervous System Metastases on Treatment Discontinuation and Survival in Older Women Receiving Trastuzumab for Metastatic Breast Cancer
Table 3
Adjusted model for risk of permanent discontinuation of trastuzumab.
Characteristic
Adjusted HR (95% CI)
P-Value
Metastases present at trastuzumab initiation
Bone
0.96 (0.72–1.27)
0.76
Liver
0.93 (0.68–1.27)
0.65
Lung/chest
0.86 (0.63–1.16)
0.32
Other
1.02 (0.74–1.40)
0.93
Diagnosed with metastases after start of trastuzumab*
CNS
1.78 (1.11–2.87)
0.02
Bone
1.17 (0.75–1.84)
0.49
Liver
1.08 (0.66–1.78)
0.76
Lung/Chest
0.76 (0.46–1.26)
0.29
Other
1.58 (0.95–2.64)
0.08
Hospital inpatient*
No
1.00 (ref)
0.49
Yes
1.34 (0.59–3.06)
Age at start of trastuzumab
66–69
1.00 (ref)
70–74
1.04 (0.70–1.54)
0.86
75–79
0.95 (0.63–1.44)
0.81
≥80
1.23 (0.81–1.87)
0.33
Need line above race/ethnicity
White
1.00 (ref)
0.20
Non-White
1.24 (0.89–1.72)
Time from MBC diagnosis to trastuzumab initiation
Per ln (days)
1.00 (0.92–1.09)
0.99
NCI comorbidity score at start of trastuzumab
0
1.00 (ref)
1
0.99 (0.62–1.60)
0.98
≥2
1.68 (0.91–3.08)
0.10
Stage at initial diagnosis
Recurrent Stage 0–III
1.00 (ref)
0.005
Incident Stage IV
0.65 (0.48–0.88)
ER/PR Status
Hormone Positive
1.00 (ref)
Hormone Negative
1.05 (0.79–1.40)
0.73
Unknown
1.14 (0.76–1.72)
0.53
Note: Asterisk (*) indicates time varying covariate. All listed covariates were included in one model. Nonwhite race includes Black, Hispanic, and Other as a combined category. Baseline defined as the date of trastuzumab initiation. Additional covariates in model that are not shown include a time-varying covariate for new cardiovascular disease and year of trastuzumab initiation (neither of which was statistically significant). Reference group for each metastasis covariate is the absence of the condition (HR = 1.0).
