***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: Purpose Peritoneal recurrence is not an uncommon cause of death after surgery for gastric cancer , even after surgery with curative intent . This indicates that there is undetected residual disease in the peritoneal cavity . We conducted this study to determine the value of peritoneal and serum carcinoembryonic antigen ( CEA ) levels and peritoneal washing cytology in predicting the locoregional and distant spread of gastric cancer . Methods We prospect ively evaluated 70 consecutive patients with gastric cancer by measuring peritoneal CEA ( pCEA ) and serum CEA ( sCEA ) levels and peritoneal washing cytology results  , and study ing their effect on the histopathologic properties . The effect of the pCEA level on disease-free survival ( DFS ) and overall survival ( OS ) was also evaluated in patients treated with curative intent . Results Twenty-one ( 30 % ) patients had sCEA levels > 10 ng/ml , whereas 25 patients ( 35.7 % ) had pCEA levels > 10 ng/g protein and 26 patients ( 37.1 % ) had positive cytology . The pCEA levels were significantly higher in patients with hepatic metastases ( P = 0.034 ) , or serosal ( P = 0.028 ) , and peritoneal ( P = 0.026 ) involvement , whereas the sCEA levels were significantly higher only in patients with hepatic metastases ( P = 0.04 ) . Similarly , positive cytology was mainly detected in patients with hepatic metastases ( P = 0.004 ) . The pCEA levels significantly affected DFS ( P = 0.002 ) and OS ( P = 0.01 ) in 34 patients treated with curative intent . ConclusionS ince pCEA levels are more useful for predicting locoregional recurrence , their measurement during surgery may help plan the most appropriate surgical strategy and adjuvant therapy We have found that elevation of preoperative serum sialyl-Tn antigen ( STN ) levels is associated with a poor prognosis for gastric cancer patients , and these high levels remain in the advanced stage of the disease . We have now examined findings with the combined assay of STN and carcinoembryonic antigen ( CEA ) levels with regard to prediction of the prognosis of gastric cancer patients .  Serum CEA levels and STN levels were determined preoperatively in 349 Japanese patients with gastric cancer . The patients were divided into four groups : ( A ) the CEA ( - ) STN ( - ) group ( CEA < or = 5 ng ml-1 , STN < or = 45 U ml-1 , n = 286 ) ; ( B ) the CEA ( - ) STN ( + ) group ( CEA < or = 5 ng ml-1 , STN > 45 U ml-1 , n = 31 ) ; ( C ) the CEA ( + ) STN ( - ) group ( CEA > 5 ng ml-1 , STN < or = 45 U ml-1 , n = 17 ) ; and ( D ) the CEA ( + ) STN ( + ) group ( CEA > 5 ng ml-1 , STN > 45 U ml-1 , n = 15 ) . Clinicopathological features and the prognosis of these groups were examined . The distribution of two markers showed no significant correlation . The patients in the CEA ( + ) STN ( + ) group ( group D ) had more advanced disease than the patients in CEA ( - ) STN ( - ) group ( group A ) ; tumour size was larger , serosal invasion was prominent , lymphatic and vascular involvement was frequent and the tumour was more infiltrative . Lymph node metastasis and hepatic metastasis were more common . Total gastrectomy was usually performed , and the non-curative rate was higher . The 5-year survival of patients in the CEA ( + ) STN ( + ) ( group D ) was 14.5 + /- 9.5 % , that is lower than that of patients in any other group [ CEA ( + ) STN ( - ) ( group C ) 44.1 + /- 12.7 % ( P < 0.05 ) ; CEA ( - ) STN ( + ) ( group B ) 60.1 + /- 9.5 % ( P > 0.05 ) ; CEA ( - ) STN ( - ) ( group A ) 77.6 + /- 9.5 % ( P < 0.05 ) ] . This combined assay of these markers will aid in estimating the prognosis and selecting appropriate drugs and care for gastric cancer patients Serum carcinoembryonic antigen ( CEA ) levels were determined serially in 30 preoperative and postoperative patients with differentiated and 47 with undifferentiated gastric cancers . Macroscopic noncurative resection of the stomach was done for those patients . There was no difference between survival curves in the differentiated and undifferentiated cases , and the 50 % survival was 13.1 months for the differentiated group and 12.5 months for the undifferentiated group . Preoperative serum CEA levels were 10.4 + /- 5.2 ng/ml for the differentiated and 4.0 + /- 1.6 ng/ml for the undifferentiated cases , and CEA-positive rates were 20.0 % for the differentiated and 14.9 % for the undifferentiated cases . There was no difference in preoperative CEA values with regard to tissue types . In the course of tumor progression , CEA levels increased during the first postoperative year in the differentiated cases and related reciprocally to decreases in survival rates . Little change was noted in the undifferentiated cases . Therefore , the serial postoperative assay of serum CEA levels has predictability with regard to tumor progression in patients with a differentiated gastric cancer BACKGROUND / AIMS The place of CA 72 - 4 , a new tumor marker in the prognosis of stomach cancer were studied , METHODOLOGY Endoscopically and histologically diagnosed 47 gastric patients were studied .  CEA , CA 19 - 9 , CA 125 , CA 15 - 3 , CA 72 - 4 levels were measured . RESULTS We determined that serum CA 72 - 4 level in the group with cancer was significantly elevated . In patients particularly having liver metastases , CA 72 - 4 level was found to be greater . CONCLUSIONS We are of the opinion that serum CA 72 - 4 level is a valuable parameter in the prognosis of stomach cancer No established second-line chemotherapy is available for patients with advanced gastric cancer failing to respond or progressing to first-line chemotherapy . However , 20–40 % of these patients commonly receive second-line chemotherapy . We evaluated the influence of clinico-pathologic factors on the survival of 175 advanced gastric cancer patients , who received second-line chemotherapy at three oncology departments . Univariate and multivariate analyses found five factors which were independently associated with poor overall survival : performance status 2 ( hazard ratio ( HR ) , 1.79 ; 95 % CI , 1.16–2.77 ; P=0.008 ) , haemoglobin ⩽11.5 g l−1 ( HR , 1.48 ; 95 % CI , 1.06–2.05 ; P=0.019 ) , CEA level > 50 ng ml−1 ( HR , 1.86 ; 95 % CI , 1.21–2.88 ; P=0.004 ) , the presence of greater than or equal to three metastatic sites of disease ( HR , 1.72 ; 95 % CI , 1.16–2.53 ; P=0.006 ) , and time-to-progression under first-line chemotherapy ⩽6 months ( HR , 1.97 ; 95 % CI , 1.39–2.80 ; P<0.0001 ) . A prognostic index was constructed dividing patients into low- ( no risk factor ) , intermediate- ( one to two risk factors ) , or high- ( three to five risk factors ) risk groups , and median survival times for each group were 12.7 months , 7.1 months , and 3.3 months , respectively ( P<0.001 ) . In the absence of data deriving from r and omised trials , this analysis suggests that some easily available clinical factors may help to select patients with advanced gastric cancer who could derive more benefit from second-line chemotherapy INTRODUCTION The clinical importance of preoperative serum levels of CA 72 - 4 , carcinoembryonic antigen ( CEA ) , CA 19 - 9 , and alpha-fetoprotein ( AFP ) was prospect ively evaluated in 44 patients with gastric cancer . METHOD The serum tumor marker levels  were determined by commercial radioimmunoassay kits . Positivity for CA 72 - 4 ( > 4 U/mL ) , CEA ( > 5 ng/mL ) , CA 19 - 9 ( > 37 U/mL ) , and AFP ( > 10 ng/mL ) were correlated according to the stage , histology , and lymph node metastasis . RESULTS AND DISCUSSION CA 72 - 4 showed a higher positivity rate for gastric cancer ( 47.7 % ) than CEA ( 25 % ) , CA 19 - 9 ( 25 % ) , and AFP ( 0 % ) . The combination of CA 72 - 4 with CEA and CA 19 - 9 increased the sensitivity to 61.4 % . The positivity rates of CA 72 - 4 in patients at stages I and II ( initial disease ) and in patients at stages III and IV ( advanced disease ) were 9 % and 60.6 % , respectively ( P < 0.005 ) . No correlation was found between CEA and CA 19 - 9 levels and the stage of gastric cancer . There was a tendency of positivity for CA 72 - 4 to suggest lymph node involvement , but it was not significant ( P = 0.075 ) . Serum levels of tumor markers did not show a correlation with the histological types of gastric cancer . CONCLUSION Preoperative serum levels of CA 72 - 4 provided a predictive value in indicating advanced gastric cancer This study was conducted to investigate the clinical utility of CEA , CA 19 - 9 , and CA-50 in the diagnosis , monitoring , and prognosis of 62 gastric carcinoma patients having either adjuvant or palliative chemotherapy .  Patients were divided in two groups : group A included patients treated  on an adjuvant basis following a curative resection of gastric cancer , and group B included patients with residual disease post surgery or patients with inoperable tumor or generalized disease .  Serum marker levels were measured in a prospect i ve study just before the initiation of chemotherapy and before each course during chemotherapy . In group A , CEA was positive in 2/25 ( 8 % ) patients , CA 19 - 9 in 1/25 ( 4 % ) , and CA-50 in 1/25 ( 4 % ) . In group B the sensitivity of CEA was 48.6 % ( 18/37 patients ) , of CA 19 - 9 64.9 % ( 27/37 patients ) , and of CA-50 70.3 % ( 26/37 ) patients . There was a significant correlation between the CA 19 - 9 and CA-50 levels in both groups . No correlation was found between the sensitivity or the absolute initial marker levels and the tumor 's differentiation or extent of disease . In group A the only patient with initially elevated CA 19 - 9 and CA-50 values relapsed early while he was on adjuvant chemotherapy . It was also found that the rising final CA 19 - 9 and CA-50 values at the end of chemotherapy were correlated with an increased incidence of relapse , but not with the disease-free interval . In group B the initially low marker levels showed a trend to predict a favorable outcome of treatment . There was no statistically significant correlation between the marker titers before each course and response to chemotherapy . It is concluded that the comeasurement of CA 19 - 9 and CA-50 , and to some degree of CEA , is justifiable for gastric cancer . The estimation of CA 19 - 9 and CA-50 may be useful for early detection of recurrence after curative surgery and adjuvant chemotherapy . In advanced or recurrent gastric cancer , the estimation of either CA 19 - 9 or CA-50 and CEA serum values may help in checking the prognosis , determining the efficacy of palliative treatment modalities , and recognizing recurrences BACKGROUND / AIMS To explore the predictive value of markers in detection of recurrence after resection . METHODOLOGY This study was a case-control retrospective analysis ; 521 patients underwent radical gastrectomy from April 2000 to January 2008 , among whom 142 cases with complete data were involved . Seventy one were confirmed with recurrence , while the other 71 without recurrence were r and omly selected from the data base as control . We analyzed the popular serum marker change patterns and their correlation with imaging . RESULTS The two groups were well balanced in characteristics . Among the 3 markers , CA72.4 appeared highest in sensitivity ( 35.2 % ) while CEA had the lowest sensitivity . The sensitivity of triple-marker was 62.0 % . We found that CEA , CA19 - 9 and CA72.4 elevated 2 - 4 months before imaging demonstration . If the cut-off values of CEA and CA19 - 9 were set twice as the upper limit of the normal , the specificities will increase to 98.6 % and 94.4 % , respectively . The sensitivity of single marker ( CEA or CA 
    Output:
    
Serum markers are not useful for early cancer , but they are useful for detecting recurrence and distant metastasis , predicting patient survival , and monitoring after surgery .
Tumor marker monitoring may be useful for patients after surgery because the positive conversion of tumor markers usually occurs 2–3 months before imaging abnormalities .
Among other tumor markers , alpha-fetoprotein ( AFP ) is useful for detecting and predicting liver metastases .
Moreover , CA125 and sialyl Tn antigens ( STN ) are useful for detecting peritoneal metastases .
Although no prospect i ve trial has yet been completed to evaluate the clinical significance of these serum markers , this literature survey suggests that combinations of CEA , CA19 - 9 , and CA72 - 4 are the most effective ways for staging before surgery or chemotherapy .
In particular , monitoring tumor markers that were elevated before surgery or chemotherapy could be useful for detection of recurrence or evaluation of the response