Screening the risk of stomach cancer based on exfoliated cells and human DNA in stool

###**Overview**
　　Stomach cancer is the fourth most common cancer and the second most common cause of cancer death. The proportion of early diagnosis is low, and most patients are diagnosed in the advanced stages. In addition to imaging screening, ctDNA in the blood and exfoliated cells in the digestive tract provide new ideas for early screening of stomach tumors.

Small amounts of blood and exfoliated cells shed into the stool from gastrointestinal tumors and the stool DNA test detects abnormal DNA. When cancer or polyps are present in the stomach, they continuously shed cells with abnormal DNA changes into the stool. Stool DNA may predict several cancers a non-invasive screening test using DNA stool samples can detect including stomach, pancreas, biliary and esophageal cancers.

Therefore, the detection and identification of abnormal DNA in feces is a potential research field.

###**Research directions**
- Screening the risk of stomach cancer based on exfoliated cells and human DNA in the stool.
- Screening the risk of stomach cancer based on the cell morphology classification in the stool.

####*Technical Route*
- Clinical sample acquisition; Preparation of smear；Cell staining; Cell recognition and edge recognition; Morphological annotation; Abnormal cell/cluster cell recognition
- Clinical sample acquisition; Cell extraction; DNA extraction; Genome and methylation sequencing; Alignment; Mutation analysis
- Clinical sample acquisition; Cell extraction; Single-cell separation; Single-cell sequencing; Alignment; Mutation analysis
 
####*EDA Route*
- Reproduction based on stool DNA data of colorectal cancer
- Based on the metagenomic data of stomach cancer patients, re-alignment and try to analyze
- Based on the data and results of some recent tumor cell recognition competitions, transfer learning in the relevant stool smear data.

###**Stomach cancer risk**
　　Many risk factors have been associated with the development of stomach cancer, and the pathogenesis is most likely multifactorial such as physical damage (food residues, foreign bodies), microbial risk (helicobacter pylori), and chemical damage risk (alcohol, various biological toxins, etc.), etc.
　　High-risk factors not only cause mutations in stomach cells but also interfere with replication behavior, making replication errors and cumulative mutations increase.

###**Stool research advantage**
　　Genome research related to stomach cancer has been carried out early, for example, the GWAS searches stomach cancer-related genes and assesses the risk of genotyping which is a mature and common method.
　　The sensitive specific antigen signal is difficult to be found which is weak and unstable.
ctDNA research and related mutation and methylation should be a hot direction, with more competition.
　　The recognition algorithm is becoming more precise to predict stomach lesions based on imaging data, including B-scan ultrasound examination, gastroscopy, CT, etc. The stomach is an organ of the digestive tract, so Stool should be attention. Cell image data in the stool could be a new data source that can be supplemented.
　　Many studies focus on relevant signals carried by the peripheral blood, and similar analysis can be carried out from the stool. The popular analysis methods and means can be used for reference, and there will be no lack of innovation. Although there are few relevant research groups on stool DNA or cell research, that is meaningful research.
　　There is a lot of information in feces that can be mutually corroborated, not only cell morphology and DNA, but also environmental information and metagenomics. Multi-omics associations would yield reliable results. At the same time, the stool is also easier to obtain information source (non-invasive), compared with gastroscopy and blood test

Furthermore, it is meaningful to perform careful cell typing based on mutations in the genome and changes in the apparent group, that could guide targeted medication and predict the direction of disease progression.

####**Reference** 
Mayo Clinic. "Improved DNA Stool Test Could Detect Digestive Cancers In Multiple Organs." ScienceDaily, 2 June 2009.

Hua Y , Bing-Qing X , Bo J , et al. Diagnostic value of stool DNA testing for multiple markers of colorectal cancer and advanced adenoma: a meta-analysis.[J]. Canadian Journal of Gastroenterology, 2016, 27(8):467-475.

Kim Y W , Kim Y H , Song Y , et al. Monitoring circulating tumor DNA by analyzing personalized cancer-specific rearrangements to detect recurrence in gastric cancer[J]. Experimental & Molecular Medicine, 2019.

Watanabe Y , Kim H S , Castoro R J , et al. Sensitive and Specific Detection of Early Gastric Cancer with DNA Methylation Analysis of Gastric Washes[J]. Gastroenterology, 2009, 136(7):2149-2158.

刁艳君, 王娟, 郝晓柯. ctDNA甲基化检测在肿瘤诊疗中的价值[J]. 中华检验医学杂志, 2019, 42(001):1-4.

“粪便里的肿瘤细胞长这样！” 中华检验医学网 https://dy.163.com/article/FBN6FLHM0514C42P.html

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