Baseline serum NTx levels are prognostic in metastatic breast cancer patients with bone-only metastasis.
BACKGROUND
There is significant heterogeneity in survival of patients with metastatic breast cancer who have bone-only metastasis. We studied the correlation of serum N-telopeptide (NTx), a marker of bone resorption, and its correlation with clinical outcomes in patients with metastatic breast cancer with bone-only or bone plus soft tissue metastasis.


METHODS
Serum was taken from 250 metastatic breast cancer patients with bone-only or bone plus soft tissue metastasis who participated in two similar randomized studies of second-line hormone therapy. An enzyme-linked immunosorbent assay specific for NTx of type I bone collagen was used to detect serum levels.


RESULTS
Sixty patients (24%) had elevated serum NTx levels, using the mean + 2 standard deviations (26 nanomoles Bone Collagen Equivalents per liter) of healthy women as a cut-off. The median duration of clinical benefit was significantly shorter in the group with elevated serum NTx levels compared with the group that had normal serum NTx levels (P=0.0004). Time to progression (TTP) was also significantly shorter in the patients with elevated serum NTx at 139 days compared with 220 days (P=0.0006). Median survival was also significantly shorter in patients with elevated baseline serum NTx levels at 663 days compared with 941 days (P<0.0001).


CONCLUSIONS
In this study, breast cancer patients with bone-only or bone plus soft tissue metastasis and elevated serum NTx levels have a shorter duration of clinical benefit, TTP and overall survival.
VA Medical Center, Lebanon, PA 17042, USA. suhail.ali@med.va.gov
S M
SM
Ali
L M
LM
Demers
K
K
Leitzel
H A
HA
Harvey
D
D
Clemens
N
N
Mallinak
L
L
Engle
V
V
Chinchilli
L
L
Costa
C
C
Brady
J
J
Seaman
A
A
Lipton
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D001859:Bone Neoplasms / Q000097:blood* / Q000556:secondary; D001862:Bone Resorption / Q000097:blood; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D003094:Collagen / Q000097:blood*; D024042:Collagen Type I; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008875:Middle Aged; D010455:Peptides / Q000097:blood*; D011379:Prognosis; D012983:Soft Tissue Neoplasms / Q000097:blood* / Q000556:secondary; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen