Although stomach cancer immunohistochemistry is similar tothe immunohistochemistry of other organ, it has great impact on diagnosis and treatment, such as its ability to reveal whether the cancer is primary or metastatic and which treatment model would be more effective in individual case. Lately, CK7, CK20 and CDX-2 immunohistochemical markers are commonly used in stomach cancers. Stomach cancer prognosis is different in each patient, depending on several factors, patients’ health status, cancer cell differentiation, and cancer cell growth. To evaluate these factors,immunohistochemic al analysis is more effective and for this purpose they use Ki-67, CD 34, BCL-2, p53, Cyclin D1, andHer- 2 markers.The evaluation of HER-2 expression should be carefully carried out, as following: 1. HER-2 expression should be evaluated on minimum 5 positive stained cells. The evaluation criteria aremicroscopic magnification and cytoplasmic membrane-stained pattern. 2. Other than the membrane-stained pattern must be excluded. HER2 gene evaluation (FISH) can confirm the HER2 IHCexpression. 3. Usage of FDA approved antibody (4B5) has the advantageof increased sensitivity. 4. The algorithm for the evaluation of HER-2 expression used for breast cancer has 50% possibility of false negativity if it is used for stomach cancer. Therefore, it is needed to beevaluated with another specific algorithm. Because HER-2 2+ and 3+ cases can improve outcome with usingTrastizumab treatment.

Introduction: Base excision repair (BER) is mainly responsible for the correction of small base changes of DNA damage. BER pathway involved many enzymes including OGG1 and XRCC1. The defective DNA repair is associated with an increased risk of various cancers including hematologic malignancies-leukemia and myelodysplastic syndrome (MDS). However, it is deniably these polymorphisms alter the susceptibility and clinical outcome of MDS patients. The aim: This study was to evaluate the impact of polymorphisms in gene encoding one protein of BER system: XRCC1 Arg399Gln in MDS and healthy population. Methods: In this study, we recruited 60 health control group [median 47.9 years, 9 MDS subjects [median 56.6 years] were included in this study. Genotyping was carried out by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Allele and genotype frequencies were calculated by direct counting. Result: The frequencies of genotypes of XRCC1 Arg399Gln were as follows: Arg /Arg 1 (11%), Arg/Gln 6 (66%), Gln/Gln 2 (22%) in MDS and Arg /Arg 18.4%, Arg/Gln40%, Gln/Gln41.6% in health control for XRCC1 Arg399Gln. The result revealed that genotypes Arg399Gln increased the risk of MDS In conclusion this study is the first to analyze XRCC1 SNPs and their associated risk of MDS in Mongolian samples. To fully understand the role of DNA damage and DNA repair in the MDS, prospective studies are needed and other genes (OGG1 Ser326Cys, MUTYH Gln324His, APE Asp148Glu) of base excision repair pathway should be analyzed.