***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: HYPOTHESIS Microsatellite instability ( MSI ) correlates with clinicopathologic characteristics and long-term prognosis in patients having gastric carcinoma . DESIGN Analysis of prospect ively collected data and biologic material . SETTING Tertiary University Hospital , Policlinico " Le Scotte , " Siena , Italy . PATIENTS Two hundred fifty patients with gastric carcinoma . MAIN OUTCOME MEASURES Five mononucleotide repeats ( BAT-26 , BAT-25 , NR-24 , NR-21 , and NR-27 ) were analyzed in these patients . RESULTS An MSI phenotype was identified in 63 patients ( 25.2 % ) and correlated with specific clinicopathologic characteristics . Favorable prognosis was confirmed for patients with an MSI phenotype in univariate ( P < .001 ) and multivariate ( P = .05 ) analyses . Significant differences in clinicopathologic characteristics and long-term prognoses were observed among patients with microsatellite-stable tumors , tumors having instability at 2 to 4 markers , and tumors having instability at all 5 markers ( MSI/5 ) . The MSI/5 phenotype was associated with older age ( P < .001 ) , female sex ( P = .001 ) , antral tumor location ( P = .04 ) , intestinal histotype ( P = .003 ) , and less infiltration of the serosa ( P = .006 ) ; lymph node involvement was rare ( P < .001 ) and was limited to few ( median , 3 ) metastatic lymph nodes ( P = .001 ) . Long-term survival of patients with the MSI/5 phenotype is favorable and was confirmed in multivariate analysis ( relative risk vs patients with stable tumors , 0.32 ; 95 % confidence interval , 0.16 - 0.63 ; P = .002 ) . CONCLUSIONS Compared with stable tumors , MSI tumors have distinct clinicopathologic features and are associated with a better prognosis . Patients with the MSI/5 phenotype have a very good prognosis The aim of this study was to clarify whether specific p53 mutations may have biological relevance in terms of disease relapse or death in gastric carcinomas ( GC ) . Resected specimens from a consecutive series of 62 patients with GC undergoing potentially curative surgery were prospect ively studied . The mutational status of exons 5 - 8 of the p53 gene was investigated in 62 cases using the PCR-SSCP and sequencing . Presence of microsatellite instability ( MSI ) was evaluated in 56 cases by analyzing loci highly sensitive of MSI . Twenty mutations of p53 were detected in 17 of the 62 cases analyzed ( 27 % ) . Ten mutations ( 50 % ) occurred in highly conserved domains . According to the p53 specific functional domains : 4/20 mutations ( 20 % ) were in the L3 loop and 3/20 ( 15 % ) in LSH motif . Eight of the 56 GC result ed MSI-H , 5 ( 9 % ) MSI-L , and 43 ( 77 % ) MSI stable ( MSS ) . None of the 8 ( 14 % ) MSI-H GC showed p53 mutations . p53 mutations were associated with intestinal histotype . Moreover , specific mutations in functional domain ( L3 and LSH ) , together with advanced TNM stage , node involvement , depth of invasion , diffuse histotype , proved to be significantly related to quicker relapse and to shorter overall survival . Specific mutations in p53 functional domains , rather than any mutations in this gene , may be biologically more significant in terms of patients outcome , indicating that these mutations might have biological relevance to identify subgroups of patients at higher risk of relapse or death who might benefit from a more aggressive therapeutic approach Aims : To evaluate the usefulness of molecular markers in predicting histopathological and clinical response to preoperative high dose chemotherapy ( HDCT ) and survival of patients with advanced gastric cancer . Methods : In a phase II trial , 25 patients with metastatic gastric cancer received preoperative t and em HDCT consisting of etoposide , cisplatin , and mitomycin , followed by autologous bone marrow transplantation to achieve surgical resectability . Sample s before and after treatment , from normal and tumour tissue , were characterised histopathologically , and both p53 and BAX expression was analysed by immunohistochemistry . Pretreatment formalin fixed , paraffin wax embedded sample s from normal and tumour tissue were microdissected , and the extracted DNA was preamplified using improved primer extension preamplification polymerase chain reaction . Detection of microsatellite instability ( MSI ) or loss of heterozygosity ( LOH ) was performed using markers for p53 , BAX , BAT25 , BAT26 , D2S123 , D17S250 , and APC . Exons 5–9 of the p53 gene were sequenced directly on ABI 373 . Results : Four parameters were significantly associated with response to chemotherapy and prolonged overall survival : positive p53 immunostaining , positive p53 mutation status before chemotherapy , strong histological regression induced by preoperative HDCT , and surgical treatment . Patients ’s sex or age , tumour location or stage , lymph node status , Lauren classification , MSI , or LOH did not influence duration of survival significantly in this high risk population . Conclusion : Positive p53 immunostaining and p53 mutation status in pretreatment tumour biopsies might be useful molecular predictors of response and prognosis in patients with advanced gastric cancer treated by preoperative HDCT 
    Output:
    
MSI gastric cancer was associated with good prognosis but there was heterogeneity in the recent studies .