From the Guidelines
Measuring type 1 collagen C-terminal telopeptide (CTX) has limited utility in cancer diagnosis, but it serves as a valuable biomarker for monitoring bone metastasis and assessing treatment response in certain cancers, particularly when used in conjunction with other markers such as N-terminal telopeptide (NTX) and bone-specific alkaline phosphatase (B-ALP) 1.
Key Points
- CTX reflects osteoclast-mediated bone resorption, which is a common feature of metabolic bone diseases, but it can also be elevated in patients with bone metastases due to cancer 1.
- The distinction between CTX and other markers like ICTP (cross-linked C-terminal telopeptide of type I collagen) lies in their generation and specificity for detecting bone involvement in malignancies 1.
- Elevated levels of CTX, NTX, and B-ALP are associated with an increased risk of skeletal-related events (SREs), disease progression, and death in patients with bone metastases 1.
- The use of bone markers like CTX, NTX, and B-ALP can help identify patients at high risk for bone metastasis or bone lesion progression, allowing for improved follow-up and early intervention 1.
- Early intervention with bone-targeted agents like denosumab and bisphosphonates can prevent or delay the onset of SREs, reduce the risk of multiple SREs, and improve overall survival in patients with bone metastases 1.
Clinical Implications
- CTX and other bone markers should not be used as standalone diagnostic tools for cancer, but rather as part of a comprehensive assessment including imaging studies and other tumor markers 1.
- Elevated CTX levels may also occur in non-malignant conditions with increased bone turnover, requiring clinical correlation for proper interpretation 1.
- The choice of bone marker and the timing of measurement should be individualized based on the patient's clinical context, tumor type, and treatment plan 1.
- Further research is needed to fully understand the role of bone markers in clinical practice and to identify the most effective strategies for using these markers to improve patient outcomes 1.
From the Research
Utility of Measuring Type 1 Collagen C-terminal Telopeptide (CTX) in Cancer Diagnosis
- CTX levels have been shown to predict the incidence of skeletal-related events in cancer patients with secondary bone metastases 2
- Serum CTX levels were found to be significantly higher in patients with disease progression and those with ≥ 5 bone metastases at diagnosis 2
- CTX has been recommended as a reference marker for bone resorption in research studies 3
Comparison with ICTP (Cross-linked C-terminal Telopeptide)
- Both CTX and ICTP have been shown to be useful indicators of skeletal metastasis status in male patients with non-small cell lung cancer 4
- ICTP had a better sensitivity and accuracy than beta-CTX in detecting bone metastases, but they had a similar area under the receiver operating characteristic curve 4
- CTX and ICTP have been used to monitor dynamic bone turnover in multiple myeloma patients, with changes in CTX-I and ICTP levels observed prior to disease progression 5
Clinical Utility of CTX in Multiple Myeloma
- CTX-1 has been shown to be a useful biomarker for monitoring myeloma bone disease (MBD) and predicting relapse 6
- CTX-1 levels were found to be higher in newly diagnosed patients compared to controls, remission, and relapse, and decreased following treatment 6
- A rise in CTX-1 levels was observed in patients prior to relapse, making it a potential tool for early detection of disease progression 6
Measurement and Harmonization of CTX Assays
- There is significant variation between different CTX assays, with plasma measurements showing more consistency than serum measurements 3
- The use of a multivariable model, including site of analysis, age, and weight of the patient, can improve the prediction of CTX results from different assays 3
- Harmonization of CTX assays is necessary to ensure accurate and reliable measurements, particularly in research studies 3