Additionally, serum concentrations of YKL-40 may be useful in the early diagnosis of gastric cancer. Table 3 Mean values of serum YKL-40 levels grouped by age in patients Seliciclib molecular weight with gastric cancer. Footnotes Disclosure This manuscript has been read and approved by all authors. This paper is unique and is not under consideration by any other publication and has not been published elsewhere. The authors and peer reviewers of this paper report no conflicts of interest. The authors confirm that they have permission to reproduce any copyrighted material.
Several cancer types are able to metastasize to organs secondary to the primary tumor. Breast, prostate, and lung cancers are the primary tumors that most frequently metastasize to the skeleton.

A metabolically active bone metastasis (BM) exerts profound effects in the local bone micro-environment, the most significant being the balance between bone resorption and bone formation-being either lytic or sclerotic metastasis.1 This results in hypocalcaemia, which in turn leads to severe bone pain and lower quality of life. Early diagnosis and treatment of BM��s might mitigate these consequences.2 Currently, BM in cancer patients is mainly diagnosed by imaging techniques such as Technetium-99 scintigraphy or x-ray.3,4 Imaging techniques are valuable diagnostic tools. However their accuracy in early diagnosis or feasibility in ongoing close monitoring of patients is limited.3 Even though scintigraphy can give quantitative information on skeletal ��hot spots�� containing BM��s, this assessment is expensive, invasive, time-consuming, and exposes cancer patients to irradiation, limiting its use for monitoring purposes.

4 Easy-to-use and accurate diagnostic tools would be valuable supplements to imaging techniques. Since biochemical markers of bone turnover can be assessed non-invasively, they could prove clinically practical in providing additional systemic information of bone turnover. A panel of markers may be selected to assess disease stages and skeletal subtype of the metastasis, and thereby provide essential information for choice of treatment. The use of bone turnover markers to detect the presence of BM��s is extensively discussed in the literature. Numerous biomarkers of bone resorption, formation, and osteoclastogenesis have been evaluated for their ability to indicate BM in cancer patients.5�C17 Some biomarkers may prove more useful than others for the evaluation of BM��s. Several studies suggest that collagenous markers may be the most reliable markers in general for the presence of BMs. Bone is a dynamic tissue which is continuously remodeled throughout life, not only to maintain Batimastat calcium homeostasis but also to repair micro-damage and thus maintain bone quality.