Diagnosis of osseous metastases of malignant tumors by bone scanning combined with bone alkaline phosphatase detection

objective To assess the diagnostic value of bone alkaline phosphatase (B-AKP) detection in diagnosis of osseous metastases of malignant tumors. Methods Bone scanning and B-AKP detection were performed in 106 patients with malignancies. According to the findings in bone imaging and clinical symptoms, the patients were divided into bone metastases group (BM) and non-bone metastases group (NBM), between whom B-AKP was compared by t test. According to the number of osseous lesions on bone imaging, the patients were graded and B-AKP was compared between the 4 grades. Correlation analysis was performed between B-AKP level and the number of osseous lesions. Results Among the 106 patients, bone scanning found osseous metastases in 68 patients. For diagnosing osseous metastases, the sensitivity, specificity, PPV and NPV of B-AKP detection were 89.7%, 52.6%' 77.2% and 74.0%, respectively. B-AKP was 28.4±14.8 μg/L in BM group and 12.8±7.6 μg/L in NBM group, showing significant difference (t=6.056, P0.001). B-AKP was 13.9±6.8 μg/L, 17.2±9.4 μg/L, 23.8±10.4 μg/L and 49.5±17.6 μg/L in patients of grade 0, 1, 2, and 3, respectively, showing significant difference by comparisons between the grades (P0.05) except for that between grades 0 and 1 (t=1.320, P05) and between grades 1 and 2 (t=1. 803, P0.05). B-AKP was 19.6±4.2 μg/L in patients with single hot focus and 13.1±3.4 μg/L in patients with single cold focus (t=2.570, P0.05). Correlation analysis showed that there was low-degree correlation between B-AKP level and the number of osseous lesions (r=0.751, P0.01). Conclusions B-AKP level detection and bone imaging yield consistent results. For diagnosis of osseous metastases in patients with malignant tumor, bone scanning is the primary choice but in cases of single hot lesions, B-AKP should be performed to prevent missed diagnosis; for false positive lesions, B-AKP should also be detected to prevent misdiagnosis.