It is speculated that adjuvant use of bisphosphonate reduces recurrence in breast cancer patients through suppression of bone resorption. To determine the prognostic impact of bone resorption markers, we investigated serum levels of the pyridinoline crosslinked carboxyterminal telopeptide of type I collagen (1CTP) and N-terminal crosslinking telopeptides of type I collagen (NTX). 1CTP and NTX were measured at baseline (before operation or neoadjuvant therapies) and afterward in 469 patients operated on breast cancer. The optimal cutoff value of 1CTP for relapse-free survival (RFS) was set at 3.6 ng/ml with an area under the receiver operating characteristics curve of 0.641 [95% confidence interval (CI) = 0.560-0.721; p = 0.0011]. However, we were unable to determine a significant cutoff value for NTX. RFS was significantly worse for 1CTP-high patients with than for those with low levels of 1CTP (p = 0.0002). Multivariate analysis with tumor size, lymph node metastasis, and nuclear grade showed that 1CTP was a significant independent prognostic factor (hazard ratio = 2.04, 95% CI = 1.13-3.68; p = 0.018). Worse prognosis for the subset with high 1CTP levels applied only to postmenopausal patients (p = 0.0002). RFS of 130 patients whose 1CTP changed from low at baseline to high at 6 months postoperatively showed RFS almost as poor as that for patients with high 1CTP throughout. These findings suggest that 1CTP may be useful not only for identifying patients with unfavorable prognosis, but also for selecting patients who may benefit from administration of bone-modifying agents in an adjuvant setting.
Keywords: 1CTP; Bisphosphonate; Bone turnover marker; Breast cancer; Metastasis.