Cross-linked type I collagen C- and N-telopeptides in women with bone metastases from breast cancer

This study documents values of biochemical markers of bone remodeling in 106 patients with breast cancer. Based on scintigraphic and radiological findings, patients were divided into 3 groups: 19 patients with bone metastases, 65 patients without bone metastases and normal bone scintigrams, and 22 patients with pathological, non-malignant findings on scintigraphy without proof of bone metastases. Urinary cross-linked type I collagen N-telopeptides (NTx) and serum cross-linked type I collagen C-telopeptides (ICTP) were assessed as markers of bone resorption. Bone alkaline phosphatase (BAP) was assessed as a marker of bone formation. All three markers were significantly higher in patients with bone metastases compared to both patients without skeletal recurrence and those with pathological, non-malignant scintigraphic findings (p < 0.01). There were no statistically significant differences between the latter two groups. The clinical sensitivity for diagnosing bone metastases was 44% for NTx, 65% for ICTP, and 26% for BAP, respectively. The clinical specificitiy for discriminating patients with bone disease from those without were 79%, 91%, and 92% for NTx, ICTP, and BAP, respectively. In conclusion, markers of bone remodeling are increased in patients with breast cancer metastatic to the skeleton. The sensitivity of the markers presented in this paper did not seem to be sufficient enough for early identification of patients with subclinical bone recurrence in a clinical practice setting.