Initial screening of gastric cancer using oral contrast-enhanced trans-abdominal ultrasonography in rural asymptomatic individuals

1Introduction

Gastric cancer (GC) remains a major challenge to the public health [1] with the fifth incidence and third mortality worldwide, according to the global cancer statistics in 2018 [2] . However, approximately half of the world’s incident and mortality cases of GC occur in China. [3] In 2015, the estimated GC incidence rate was 6.79 per 100,000 and estimated mortality rate was 4.98 per 100,000, roughly 1364 deaths per day. [4] Moreover, the 5-year survival rate of GC was low in China because more than 80 % of patients were diagnosed at the advanced stages due to the absence of specific symptoms [5] . Thus, early diagnosis and treatment are very crucial to reduce the mortality of GC. However, the early detection relies on opportunistic screening only [6] . Since 2008, the screening programs for early detection of upper gastrointestinal diseases have been launched in selected high-risk areas of China, including the national Upper Gastrointestinal Cancer Early Detection (UGCED) program and Cancer Screening Program in Urban China (CanSPUC) [7] .

Currently, gastroscopy with sampling of gastric biopsies for histopathological examination is the gold standard for GC diagnosis [8] . The early detection of GC has been over 50 % in the United States and East Asian countries (e.g., Japan and Korea) with government-sponsored screening program by barium fluorography or endoscopy [89] . Compared to these countries, GC patients in China had larger tumors, a later stage at presentation, and worse outcome [10] . Although there is no nationwide screening program of GC, the current guideline recommends the screening beginning at age 40 years for the high-risk population. However, more than 45 % of the population in China is aged over 40 years, it is not feasible to offer gastroscopy screening to all in this population considering the high cost as well as limited clinical resources of technicians and gastroscopy equipments [11] . Moreover, uncomfortable feelings and even fear of gastroscopy make it difficult to be accepted in a wide population, in particular for elderly people in rural area who did not have public health education of early diagnosis and prevention of diseases. Thus, considering the large population in China and the necessity of wide acceptability, it is better to provide a non-invasive screening strategy that could be accurate, reliable, cost-effective, and publicly acceptable in a wide population.