The Feasible Research of Infrared Endoscope to Diagnose Early Gastric Cancer and Evaluate the Invasive Depth of Tumors

The gastric cancer is the second most frequently diagnosed cancer and the third leading cause of cancer death in China.80%-90% patients were detected at middle and later stage.The five-year survival rate for advanced gastric cancer patients is less than 10% due to the shortage of effective treatment method.The five-year survival rate for early gastric cancer patients is beyond 90%.The reason for poor diagnosis and treatment is that current methods do not achieve the diagnosis of early gastric cancer.Endoscopy with biopsy is still the main method for confirming gastric cancer.But it is limited to identify early gastric cancer and it leads to the low diagnostic rate of early gastric cancer.

Accurate diagnosis for early gastric cancer and the pretherapeutic estimation of the invasion depth is desired to determine suitable treatment.Presently,endoscopic submucosal dissection is the new effective minimally invasive treatment for early gastric cancer,which preserve the entire stomach and improve the patient's postoperative quality of life.But the estimation of invasion depth of gastric cancers should be confirmed before operation.

Recently,some research suggest that narrow banding imaging and endoscopy ultrasonography are considered established means of diagnosis for early gastric cancer and depth.No formal quantitative review of the available evidence has been published that narrow banding imaging or endoscopy ultrasonography could accurately diagnose early gastric cancer and evaluate the invasive depth.This means still has great limitations.The sensitivity of narrow banding imaging diagnosis is only 60% which its high false positive rate,shorter wavelength and lighter penetration,and the result is influenced by histologic variety of early gastric cancer and inflammatory changes in the background mucosa;Although endoscopy ultrasonography achieves a diagnostic accuracy of over 80%,and its tomographic views facilitate objective assessments,it is occasionally difficult to obtain images with adequate quality, and its evaluation is highly dependent on operators' proficiency levels.

Infrared endoscopic imaging is a new great potential method of diagnosis of early gastric cancer, since the first report in the 1990 s, people have been exploring in this field. Through intravenous injection of exogenous contrast medium, such as the indocyanine green, it makes mucosal lesions highlight,and avoids the interference of background light.If specific target molecular is linked to the contrast medium,the specific imaging of the lesion can be presented. What is more,due to the strong penetration power of infrared light,its imaging depth also increases significantly.Indocyanine green had also been demonstrated safe in clinical studies and widely used, such assessment of liver function tests.

At present,the research in this aspect is very few, a few clinical research results show that infrared endoscopic imaging has a larger value for differentiating between early gastric cancer and gastric adenoma, and the difference between early gastric cancer and gastric lesions is significantly correlated with the depth of cancer invasion.