The prevalence of  bone metastasis in patients with gastric cancer : A systematic review and meta-analysis

Objective: To assess the prevalence of bone metastasis in patients with gastric cancer systematically. Methods: : Literatures that reported prevalence rates of bone metastasis in patients with gastric cancer were identified via PubMed, China National Knowledge Infrastructure (CNKI), Wanfang database and Weipu database from inception to October 2018. The methodological quality of the included studies was evaluated by Agency for Healthcare Research and Quality (ARHQ). Subgroup analyses were performed stratified by areas, years of publication, Tumor Node Metastasis (TNM) stages, pathological types and clinical characteristics. Publication bias was assessed with Egger’s test and Begg’s funnel plot. Results: : A total of 59 studies were eligible for inclusion and the methodological qualities of included studies were moderate to high. The pooled prevalence of bone metastasis in patients with gastric cancer was 8.1% (95%CI: 7.0%, 9.1%). Of all the included studies, thirty-three studies were conducted in China, and the pooled prevalence of China was 10.6%. From 1996 to 2000, the prevalence was 10.8% (95%CI: 5.6%, 16.1%), and it increased to 17.4% (95%CI: 8.5%, 26.3%) from 2001 to 2005. After that till now, the prevalence drastically decreased and maintained at a low level around 5.9%. The prevalence showed an increasing trend from 2.7% (95%CI: 0.0%, 5.4%) to 38.5% (95%CI: 20.6%, 56.3%) from TNM stage Ⅰ to stage Ⅳ. The prevalence was 4.5% (95%CI: 1.7%, 7.4%) in the well and moderately differentiated group, 19.0% (95%CI: 13.8%, 24.1%) in the poorly differentiated and undifferentiated group, 31.6% (95%CI: 2.9%, 60.3%) in the signet ring cell group, and 19.3% (95%CI: 11.8%, 26.9%) in the mucinous group, respectively. Conclusion: The pooled prevalence of bone metastasis in patients with gastric cancer was 8.1%. The prevalence increased with the exacerbation of gastric cancer from TNM stage Ⅰ to stage Ⅳ and was inversely related to the degree of tissue differentiation. At the same time, it was also affacted by area and years.