Bone turnover markers in women with early stage breast cancer who developed bone metastases. A prospective study with multivariate logistic regression analysis of accuracy.

Background: The skeleton is the most common site of metastasis for breast cancer and the periodic measurement of circulating bone turnover markers (BTMs) can be useful. The aim of this study was to prospectively evaluate the diagnostic accuracy of a panel of BTMs in the early detection of bone metastases (BMs).

Methods: We reviewed the medical records of 297 postmenopausal women with early stage luminal-type invasive ductal carcinoma (IDC). Twenty-six patients who developed isolated BMs during follow-up and 24 randomly selected controls were studied. The two groups were matched according to age, final disease staging, and follow-up. All patients underwent periodic measurement of total and bone-specific (BSAP) alkaline phosphatase, CTX, ICTP, osteocalcin, NTX, PINP, and TRACP5b.

Results: Only BSAP, CTX, PINP, and TRACP5b were significantly (p<0.05) associated with the group, and the logistic regression analysis excluded CTX from the model. The AUC (ROC curve) for TRACP5b alone, which was the most accurate marker, and for the combination of BSAP+PINP+TRACP5b was 0.784 (95% CI: 0.651-0.916) and 0.889 (95% CI: 0.798-0.981), respectively.

Conclusion: According to our results, the measurement of these three markers together should be performed in all postmenopausal patients with luminal-type IDC, when an early diagnosis of BMs is required.