Clinical study on SUVmax combined with ALP, N-MID, TPINP and BMD in the early diagnosis of lung cancer bone metastasis

Objective: In combination with Maximum Standardized Uptake Value (SUVmax) from SPECT/CT scans in lung cancer patients, serum alkaline phosphatase (ALP), molecular fragments in the N end of osteocalcin (N-MID), total procollagen type 1 N-terminal propeptide (TPINP), and bone mineral density (BMD) measurements to explore the clinical early diagnosis of lung cancer bone metastasis. Methods: A total of 107 patients diagnosed as lung cancer at a tertiary-level Class A hospital between January 2021 and June 2022 were enrolled, comprising 37 cases with bone metastasis and 70 cases without bone metastasis. All patients underwent relevant examinations. SPECT/CT was performed in the supine position with anterior and posterior whole-body bone imaging, using a matrix of 256 × 1,024, an energy peak of 140 keV, and a window width of 20%. SUVmax was measured. BMD measurement utilizes dual-energy X-ray absorptiometry to assess the first to fourth lumbar vertebrae, bilateral femoral necks, and total hip joints in the examinees, yielding bone mineral content per unit area (g/cm2). Fasting blood samples in the morning were taken and a fully automated biochemical analyzer was used to measure ALP levels, and a fully automated chemiluminescence immunoassay analyzer was used to measure serum N-MID and TPINP levels. Results: Patients with bone metastasis exhibited ALP, N-MID and TPINP levels of 120.30 ± 33.32 U/L, 19.03 ± 3.54 mg/L and 82.21 ± 26.65 mg/L, respectively, significantly higher than those in patients without bone metastasis (94.43 ± 30.30 U/L, 15.50 ± 4.01 mg/L, 55.58 ± 21.01 mg/L), p < .001, indicating a significant difference; The lumbar spine BMD in patients with bone metastasis was 0.82 ± 0.12 g/cm2, compared to 0.89 ± 0.14 g/cm2 in patients without bone metastasis, p = .011, demonstrating a statistical significance. Comparisons between patients with and without bone metastasis revealed no statistically significant differences in gender, pathological type, femoral neck BMD, or whole-body BMD (p > .05). The SUVmax value for adenocarcinoma patients was 11.45 ± 1.98, significantly lower than 13.51 ± 2.00 for patients with squamous cell carcinoma and 13.98 ± 2.02 for other types (p < .001), representing a statistically significant difference. For patients with tumors with diameter > 5 cm and TNM stage III–IV, SUVmax values were 13.38 ± 1.95 and 12.99 ± 2.00, respectively, significantly higher than those with tumors ≤ 5 cm (11.50 ± 2.01) and TNM stage I–II (11.77 ± 1.93), with p < .001 and p = .002, respectively, demonstrating a statistical significance. Comparison in SUVmax of gender and age showed p > .05, indicating no statistically significant difference. In patients with TNM stage III–IV, ALP, N-MID and TPINP levels were 110.39 ± 21.12 U/L, 18.62 ± 2.22 mg/L and 70.31 ± 17.02 mg/L, respectively, significantly higher than those in patients with TNM stage I–II (97.45 ± 19.82, 15.12 ± 2.14 and 60.12 ± 15.65, respectively. The corresponding p values were .001, < .001 and .002, indicating a statistical significance. Comparison in ALP, N-MID and TPINP levels among patients of different genders, ages, pathological types and tumor diameters showed p > .05, indicating no statistically significant differences. The areas under the ROC curves for ALP, N-MID and TPINP in the diagnosis of bone metastasis were 0.695, 0.734 and 0.837, respectively, with p < .05. Conclusions: Serum ALP, N-MID and TPINP levels were significantly elevated in patients with bone metastasis of lung cancer in comparison to those without bone metastasis, while SUVmax showed no significant difference. SUVmax, ALP, N-MID and TPINP are associated with certain clinical and pathological characteristics in lung cancer patients. Among these, ALP, N-MID and TPINP demonstrate a potential diagnostic value for detecting bone metastasis in lung cancer.