18F-FDG PET/CT在胃癌骨转移中的临床应用

  目的  探讨胃癌骨转移患者的临床特征以及18F-FDG PET/CT在胃癌骨转移中的临床应用。  方法  选择2010年1月~2020年12月在中山大学肿瘤防治中心治疗前行18F-FDG PET/CT检查且原发灶经病理确诊的21例胃癌骨转移患者，其中男性9例、女性12例，中位年龄57.0（28.0，81.0）岁，回顾性分析其临床资料及18F-FDG PET/CT定性、半定量[最大标准化摄取值（SUV_max）] 指标特点。根据原发灶组织分化情况，将患者分为:低分化组13例（65.0%）和中-低分化组7例（35.0%）。根据Lauren分型，将患者分为:肠型组4例（20.0%），混合型组9例（45.0%），弥漫型组7例（35.0%）。根据Soloway分级将骨转移灶数量分为3组（Ⅰ级≤5，Ⅱ级6~20，Ⅲ级 > 20）:Ⅰ级（组）6例，Ⅱ级（组）4例，Ⅲ级（组）11例。根据PET/CT上溶骨性、混合性及成骨性表现将骨转移类型分为3组:纯溶骨性转移6例，混合性（溶骨性/成骨性）11例，成骨性4例。  结果  本组胃癌患者发生骨转移部位依次为脊柱（19/21），肩胛骨、肋骨、锁骨、胸骨（18/21）及骨盆（17/21），其中3例伴有骨髓浸润。患者同期血清碱性磷酸酶升高11例（57.9%），乳酸脱氢酶升高7例（36.8%）。不同骨转移类型组间乳酸脱氢酶水平存在差异（χ2=6.823，P=0.047），混合性转移乳酸脱氢酶升高更常见。骨转移灶SUV_max大小在性别、Lauren分型及Soloway分级的差异有统计学意义（Z=-1.990，H=6.326，H= 6.070，P < 0.05）；女性组中位SUV_max为11.6(7.3, 32.1)，高于男性组的7.2(3.7, 17.1)；弥漫型[12.2(5.3, 32.1)]及混合型组[10.8 (7.2, 17.2)]高于肠型组[6.7(3.7, 7.3)]；Soloway分级越高，即骨转移数目越多，骨转移灶的SUV_max越高。Soloway分级在性别上存在差异（χ2=6.832，P=0.033），女性患者Soloway分级普遍高于男性。原发灶及骨转移灶SUV_max大小与年龄有关，低龄组（< 中位年龄57.0岁）骨转移灶SUV_max多较高而原发灶SUV_max多较低（χ2=5.838、10.831，P < 0.05）。  结论  18F-FDG PET/CT能够全面评估胃癌骨转移情况。胃癌骨转移具有一定的特点，常发生于中轴骨，以溶骨性及多灶转移多见，常伴有乳酸脱氢酶、碱性磷酸酶的升高。乳酸脱氢酶升高更常见于混合性骨转移患者。 

Clinical application of 18F-FDG PET/CT in bone metastases from gastric cancer

  Objective  To explore the clinical characteristics of patients with bone metastases from gastric cancer and the clinical application of 18F-FDG PET/CT in bone metastasis from gastric cancer.  Methods  From January 2010 to December 2020, 21 gastric cancer patients with bone metastases from gastric cancer who had undergone 18F-FDG PET/CT before treatment at the Cancer Prevention and Treatment Centre of Sun Yat-sen University and whose primary foci were pathologically confirmed, including 9 males and 12 females with a median age of 57.0 (28.0, 81.0) years old. The clinical data and the characteristics of the 18F-FDG PET/CT qualitative and semi-quantitative (maximum standardized uptake value SUV_max) index were retrospectively analyzed. According to the tissue differentiation of the primary foci, the patients were divided into: 13 cases (65.0%) in the hypofractionated group and 7 cases (35.0%) in the intermediate-hypofractionated group. According to the Lauren typing, the patients were divided into: 4 cases (20.0%) in the intestinal group, 9 cases (45.0%) in the mixed group and 7 cases (35.0%) in the diffuse group. According to Soloway classification, the number of bone metastases was divided into 3 groups (class Ⅰ≤5, class Ⅱ 6-20, class Ⅲ > 20), including 6 cases of class (group) Ⅰ, 4 cases of class (group) Ⅱ, and 11 cases of class (group) Ⅲ. Bone metastasis types were divided into 3 groups according to the manifestations on PET/CT (osteolytic, mixed, and osteogenic). There were 6 cases of pure osteolytic metastasis, 11 cases of mixed(osteolytic/osteogenic), and 4 cases of osteogenic metastasis.  Results  In this group of patients with gastric cancer, bone metastases occurred in the spine (19/21), scapula, ribs, collarbone, sternum (18/21), and pelvis (17/21), of which 3 cases were accompanied by bone marrow infiltration. The serum alkaline phosphatase and lactate dehydrogenase were elevated in 11 cases (57.9%) and 7 cases (36.8%) during the same period. There were differences in lactate dehydrogenase levels between different types of bone metastasis (χ2=6.823, P=0.047), with elevated lactate dehydrogenase being more common in mixed metastases. There were statistically significant differences in the SUV_max of metastatic bone lesions in gender, Lauren's classification, and Soloway classification (Z=-1.990, H=6.326, H=6.070, all P < 0.05). The median SUV_max 11.6 (7.3, 32.1) in the female group was higher than that in the male group [7.2 (3.7, 17.1)]; The diffuse-type group [12.2 (5.3, 32.1)] and the mixed-type group [10.8 (7.2, 17.2)] were higher than the intestinal-type group [6.7 (3.7, 7.3)]. The higher the Soloway classification, i.e. the higher the number of bone metastases, the higher the SUV_max of metastatic bone lesions. There was a difference in the Soloway grading by gender (χ2=6.832, P=0.033), with female patients generally having a higher Soloway grade than males. Primary and bone metastases SUV_max size was age dependent, with the lower age group (< median age 57.0 years) having higher bone metastases SUV_max and lower primary SUV_max. (χ2=5.838, 10.831, P < 0.05).  Conclusion  18F-FDG PET/CT can provide a comprehensive assessment of bone metastases from gastric cancer. Bone metastasis from gastric cancer have specific characteristics, such as often occurring in the mid-axis bone, with osteolytic and multifocal metastases commonly and are often associated with elevated lactate dehydrogenase and alkaline phosphatase. Elevated lactate dehydrogenase is more common in patients with mixed bone metastases.