目前我国每年平均200万新增癌症患者中有50-60%最终发生骨转移，癌细胞骨转移容易引起病理性骨折、恶性高钙血症和骨髓浸润等多种骨相关事件，导致患者的中位生存时间仅为8-10个月。因此，深入研究癌症骨转移机制，建立癌症患者骨转移的早期预警体系，对合理选择治疗方式预防癌细胞骨转移，提高癌症的治愈率有着重要的临床意义。. 然而，由于灵敏度的限制，传统诊断手段对癌细胞骨转移早期诊断的效果并不理想。为了更灵敏地分析早期骨转移过程中骨骼代谢机制，最大程度地提前癌细胞骨转移的检出时间，本项目拟采用高灵敏度41Ca-AMS同位素示踪技术，以裸鼠为实验对象，加速器质谱作为测量手段，研究和探讨在癌细胞刺激下裸鼠在不同时间段(特别是前期)的骨骼代谢行为，得出41Ca代谢曲线与癌细胞扩散程度及骨转移的关系，建立采用41Ca早期诊断和监测癌细胞骨转移的高灵敏技术方法，为临床癌症骨转移的防治提供重要的科学依据。

The annual incidence of new cancer patients in China is about 2 million, 50-60% of which will end up with bone metastasis. The bone metastasis of cancer usually causes a variety of bone-related events, such as the pathological fracture, malignant hypercalcemia and bone marrow infiltration, which lead to the shortened median survival time (8-10 months) for the metastasis patients. So, profound study on the mechanism and early diagnosis of cancer bone metastasis are very significant for the prevention and treatment of bone metastasis and the improvement of the survival rates for cancer patients.. Due to their limited sensitivities, traditional methods in early diagnosis of bone metastasis of cancer cells do not work very well. In order to monitor the processes of bone metabolism and early detection of bone metastasis of cancer cells, a technique of 41Ca isotope tracer combined with highly sensitive accelerator mass spectrometry will be developed and applied in the study on the bone metastasis of cancer cells by nude mice simulation. Taking the advantages of high sensitivity, fast analysis speed, and small sample size requirement, the 41Ca-AMS technique developed in this work is expected to provide an important scientific basis for the early diagnosis, prevention and treatment of bone metastases of cancer cells in clinical medicine.