gastric cancer is the fourth leading cause of cancer deaths worldwide ( 1 ) and the third in china ( 2 ) . missed preoperative diagnosis of intra - abdominal metastases , including 
 peritoneal dissemination and intraperitoneal free cancer cells , is among the leading cause 
 of poor prognosis , surgical failure and futile laparotomy . therefore , accurate preoperative 
 staging , especially through improved diagnostic accuracy of peritoneal dissemination and 
 intraperitoneal free cancer cells , is particularly important for alternative treatment 
 strategies and prognostic evaluations . as an alternative of laparotomy , diagnostic laparoscopy has been suggested to effectively 
 detect peritoneal diseases and can be used to collect peritoneal lavage fluid for cytology 
 examination with minimal invasion . however , diagnostic laparoscopy plays a currently 
 undefined role in gastric cancer staging due to controversy regarding its indications . national comprehensive cancer network ( nccn ) guidelines recommend laparoscopic staging for 
 patients with t3 and/or n+ if they are considered for surgical resection without 
 preoperative therapy ; european society for medical oncology ( esmo ) guidelines recommend 
 laparoscopic staging for patients with ib - iii gastric cancer ; and japanese gastric cancer 
 association ( jgca ) guidelines mention only laparoscopy prior to neoadjuvant 
 chemoradiotherapy ( 3 - 5 ) . in china , most gastric cancer patients present with advanced disease stages ; 
 however , a consensus on the role of diagnostic laparoscopy still has not been established 
 because of the lack of direct evidence ( 6 ) . the aim of this study was to provide an assessment of the detection rate of intra - abdominal 
 metastasis using diagnostic laparoscopy in gastric cancer patients , and investigate the 
 clinical risk factors of intra - abdominal metastasis before exploratory operation to 
 determine the indications of diagnostic laparoscopy for patients with gastric cancer in 
 china . between september 2011 and september 2013 , a prospective study of pretherapeutic 
 diagnostic laparoscopy was performed on consecutive gastric cancer patients in the 
 department of gastrointestinal surgery at the peking university cancer hospital 
 ( figure 1 ) . basic algorithm for selection and treatment of patients with locally advanced gastric 
 cancer . patients meeting the inclusion criteria were enrolled , and the following data were 
 recorded : basic information , including age , gender , height , body weight and weight loss ; 
 and clinical information , including results of endoscopy , computed tomography ( ct ) , 
 endoscopic ultrasound ( eus ) and result of blood test . more specifically , borrmann type , 
 proportion of the tumor in relation to circumference of the stomach ( < 1/4 , 1/4 to 
 < 1/2 , 1/2 to < 3/4 , and 3/4 ) and portions of stomach ( cardia , fundus , body and 
 antrum ) were determined by endoscopy ; t stage , n stage , tumor depth , basal diameter and 
 basal area were from eus ; and serosal invasion , enlarged lymph node , and tumor depth were 
 measured by ct . tumor markers [ carcinoembryonic antigen ( cea ) , carbohydrate antigen 19 - 9 
 ( ca19 - 9 ) , ca72 - 4 , and ca242 ] were determined by blood test . we adopted a ct criteria described by jin woong kim to measure serosal invasion on ct . specifically , when an irregular or nodular outer margin of the outer layer and/or a dense 
 band - like perigastric fat infiltration was visualized , serosal invasion was suspected 
 ( 7 ) . depth of invasion was measured using ct slices as shown in figure 2 . to maintain consistency of degree of 
 distension , a gas distension method was used during ct scan ( 8) . measurement of the depth of invasion on ct . measurement of the depth , the basal diameter and basal area are shown in figure 3 . lymph nodes were considered 
 positive for metastasis if they were equal to or larger than 8 mm in the short - axis 
 diameter under eus ( 9 ) . ( a ) depth and 
 basal diameter ; ( b ) basal area . this study is conducted in accordance with the  declaration of helsinki  and  ethical 
 guidelines for clinical research  , and has been approved by the institutional review 
 boards of peking university cancer hospital . the inclusion criteria included : 1 ) histologically confirmed diagnosis of primary gastric 
 carcinoma ; 2 ) abdominal enhanced spiral ct and eus showed a clinical stage of ct2 - 4n0 - 3m0 ; 
 3 ) fit for radical gastrectomy or neo - adjuvant treatment ; and 4 ) agree to have diagnostic 
 laparoscopy . the exclusion criteria included : 1 ) unfit for laparoscopic operation or general 
 anesthesia ( suspicious abdominal adhesions , severe cardiopulmonary disease , etc . ) ; 2 ) 
 underwent emergency surgery to relieve obstruction , bleeding or perforation ; or 3 ) 
 preoperative examination shows signs of metastasis , including peritoneal thickening , 
 ascites , distant lymph node enlargement , etc . a 10-mm disposable trocar ( observing hole ) was inserted into the sub - umbilicus , 
 and a 30 telescope was used . another 10-mm trocar and a 5-mm trocar ( operating hole ) were 
 inserted into the right and left upper quadrants , respectively . prior to any manipulation , 
 250 ml of warm normal saline was infused into the subphrenic space , subhepatic space , 
 omentum , bilateral paracolic sulci and the pouch of douglas . care was taken to avoid 
 direct contact of the irrigation with the primary tumor . at least 100 ml of fluid was 
 aspirated from the subphrenic space , subhepatic space and pouch of douglas . subsequently , a 
 systematic inspection of the abdominal cavity was performed clockwise from the right 
 quadrant . patients without macroscopic peritoneal dissemination ( p ) and with negative 
 cytology results ( cy ) were defined as having negative diagnostic laparoscopy 
 results ( dl ) , which means there are no intra - abdominal metastases . and patients 
 with peritoneal dissemination , which was confirmed by frozen pathology ( p+ ) or free cancer 
 cells in the peritoneal lavage ( cy+ ) , were defined as having positive diagnostic 
 laparoscopy results ( dl+ ) . to determine the clinical risk factors as predictors for gastric cancer patients with 
 intra - abdominal metastasis before exploratory operation , a split - sample method was 
 applied . the patient cohort was divided randomly into 2 groups : 3/4 for a training set and 
 1/4 for a testing set . in the training set , the clinical characteristics of the dl 
 and dl+ patients were compared using the independent samples group t - test 
 and chi - squared test . to determine the risk factors , all variables found to be significant 
 by univariate analysis were assessed by binary logistic regression analysis ( method : 
 backward wald , probability for stepwise : 0.5 for entry , 1.0 for removal ) . the receiver 
 operating characteristic ( roc ) curve and area under the curve ( auc ) analyses were used to 
 determine sensitivity , specificity and corresponding cut - off values of each factor . in the 
 testing set , all patients were classified according to their number of risk factors 
 determined by training set , and the sensitivity and specificity of different combinations 
 of factors were calculated to predict the metastasis . all statistical analyses were carried out using the ibm spss 
 statistical ( version 20.0 ; ibm corp . between september 2011 and september 2013 , a prospective study of pretherapeutic 
 diagnostic laparoscopy was performed on consecutive gastric cancer patients in the 
 department of gastrointestinal surgery at the peking university cancer hospital 
 ( figure 1 ) . basic algorithm for selection and treatment of patients with locally advanced gastric 
 cancer . patients meeting the inclusion criteria were enrolled , and the following data were 
 recorded : basic information , including age , gender , height , body weight and weight loss ; 
 and clinical information , including results of endoscopy , computed tomography ( ct ) , 
 endoscopic ultrasound ( eus ) and result of blood test . more specifically , borrmann type , 
 proportion of the tumor in relation to circumference of the stomach ( < 1/4 , 1/4 to 
 < 1/2 , 1/2 to < 3/4 , and 3/4 ) and portions of stomach ( cardia , fundus , body and 
 antrum ) were determined by endoscopy ; t stage , n stage , tumor depth , basal diameter and 
 basal area were from eus ; and serosal invasion , enlarged lymph node , and tumor depth were 
 measured by ct . tumor markers [ carcinoembryonic antigen ( cea ) , carbohydrate antigen 19 - 9 
 ( ca19 - 9 ) , ca72 - 4 , and ca242 ] were determined by blood test . we adopted a ct criteria described by jin woong kim to measure serosal invasion on ct . specifically , when an irregular or nodular outer margin of the outer layer and/or a dense 
 band - like perigastric fat infiltration was visualized , serosal invasion was suspected 
 ( 7 ) . depth of invasion was measured using ct slices as shown in figure 2 . to maintain consistency of degree of 
 distension , a gas distension method was used during ct scan ( 8) . measurement of the depth of invasion on ct . measurement of the depth , the basal diameter and basal area are shown in figure 3 . lymph nodes were considered 
 positive for metastasis if they were equal to or larger than 8 mm in the short - axis 
 diameter under eus ( 9 ) . this study is conducted in accordance with the  declaration of helsinki  and  ethical 
 guidelines for clinical research  , and has been approved by the institutional review 
 boards of peking university cancer hospital . the inclusion criteria included : 1 ) histologically confirmed diagnosis of primary gastric 
 carcinoma ; 2 ) abdominal enhanced spiral ct and eus showed a clinical stage of ct2 - 4n0 - 3m0 ; 
 3 ) fit for radical gastrectomy or neo - adjuvant treatment ; and 4 ) agree to have diagnostic 
 laparoscopy . the exclusion criteria included : 1 ) unfit for laparoscopic operation or general 
 anesthesia ( suspicious abdominal adhesions , severe cardiopulmonary disease , etc . ) ; 2 ) 
 underwent emergency surgery to relieve obstruction , bleeding or perforation ; or 3 ) 
 preoperative examination shows signs of metastasis , including peritoneal thickening , 
 ascites , distant lymph node enlargement , etc . a 10-mm disposable trocar ( observing hole ) was inserted into the sub - umbilicus , 
 and a 30 telescope was used . another 10-mm trocar and a 5-mm trocar ( operating hole ) were 
 inserted into the right and left upper quadrants , respectively . prior to any manipulation , 
 250 ml of warm normal saline was infused into the subphrenic space , subhepatic space , 
 omentum , bilateral paracolic sulci and the pouch of douglas . care was taken to avoid 
 direct contact of the irrigation with the primary tumor . at least 100 ml of fluid was 
 aspirated from the subphrenic space , subhepatic space and pouch of douglas . subsequently , a 
 systematic inspection of the abdominal cavity was performed clockwise from the right 
 quadrant . patients without macroscopic peritoneal dissemination ( p ) and with negative 
 cytology results ( cy ) were defined as having negative diagnostic laparoscopy 
 results ( dl ) , which means there are no intra - abdominal metastases . and patients 
 with peritoneal dissemination , which was confirmed by frozen pathology ( p+ ) or free cancer 
 cells in the peritoneal lavage ( cy+ ) , were defined as having positive diagnostic 
 laparoscopy results ( dl+ ) . to determine the clinical risk factors as predictors for gastric cancer patients with 
 intra - abdominal metastasis before exploratory operation , a split - sample method was 
 applied . the patient cohort was divided randomly into 2 groups : 3/4 for a training set and 
 1/4 for a testing set . in the training set , the clinical characteristics of the dl 
 and dl+ patients were compared using the independent samples group t - test 
 and chi - squared test . to determine the risk factors , all variables found to be significant 
 by univariate analysis were assessed by binary logistic regression analysis ( method : 
 backward wald , probability for stepwise : 0.5 for entry , 1.0 for removal ) . the receiver 
 operating characteristic ( roc ) curve and area under the curve ( auc ) analyses were used to 
 determine sensitivity , specificity and corresponding cut - off values of each factor . in the 
 testing set , all patients were classified according to their number of risk factors 
 determined by training set , and the sensitivity and specificity of different combinations 
 of factors were calculated to predict the metastasis . all statistical analyses were carried out using the ibm spss 
 statistical ( version 20.0 ; ibm corp . from september 2011 to september 2013 , 249 patients with histologically confirmed gastric 
 carcinoma underwent diagnostic laparoscopy with peritoneal cytology examination as a 
 routine pretreatment workup , 70.7% of whom are males , with a median age of 57.6 ( range : 
 2981 ) years . on the basis of ct and eus findings , 13 ( 5.2% ) patients were found to 
 have clinical stage i disease , 64 ( 25.7% ) were stage ii disease , and 172 ( 69.1% ) were 
 stage iii disease . for t stage , 15 ( 6.0% ) patients were t2 , 65 ( 26.1% ) were t3 and 169 
 ( 67.9% ) were t4 . as for n stage , 53 ( 21.3% ) patients were n0 , and 196 ( 78.7% ) were n+ . from the diagnostic laparoscopy findings , 14 ( 5.6% ) of the 249 patients had visible 
 peritoneal dissemination only , which was confirmed by frozen pathology , 17 ( 6.8% ) had free 
 cancer cells in the peritoneal lavage only and 20 ( 8.0% ) had both metastases . in total , 51 
 ( 20.5% ) patients were dl+ and 198 were dl. among the dl+ patients , 42 underwent 
 hyperthermic intraperitoneal chemotherapy ( hipec ) followed by palliative chemotherapy 
 after diagnostic laparoscopy , and 9 underwent palliative surgery . among the dl 
 patients , 101 underwent radical d2 gastrectomy , and 97 underwent neoadjuvant 
 chemotherapy . the split sample method was used , and the 249 patients were divided into two sets using 
 random sampling : 3/4 ( 187 patients ) as a training set for developing predictive factors of 
 metastasis and 1/4 ( 62 patients ) as a testing set for validating these factors . the clinical characteristics were compared between the dl+ and dl patients 
 ( table 1 ) . in the training 
 set , 38 ( 20.3% ) patients were dl+ , and 149 patients were dl. ca72 - 4 expression , 
 proportion of the tumor in relation to the circumference of the stomach , tumor - occupied 
 stomach portions , borrmann type , depth of tumor invasion on ct and depth of tumor invasion 
 on eus were found to be significant in our univariate analyses . next , all these factors 
 were evaluated by multivariate analysis . among these factors , multivariate analysis 
 indicated that the depth of tumor invasion on ct scan and tumor - occupied stomach portions 
 are predictive factors of metastasis ( table 
 2 ) . clinicopathologic features of dl+ and dl patients ( univariate analysis , 
 training set )   predictive factors of metastasis ( multivariate analysis , training set )   from an roc curve ( figure 4 , 5 and table 3 ) , the highest youden index ( 0.217 and 0.270 , 
 respectively ) was obtained when the depth of tumor invasion on ct was cut off at 21 mm 
 ( auc : 0.668 , p<0.01 ) and tumor - occupying portions of the stomach were cut off between 
 1 and 2 ( auc : 0.676 , p<0.01 ) . roc for the prediction of intra - abdominal metastasis by the depth of tumor invasion 
 found by ct scans . roc for the prediction of intra - abdominal metastasis by the tumor occupying portions 
 of stomach . prediction of intra - abdominal metastasis by the depth of tumor invasion found by ct 
 scans and the tumor - occupied portions of stomach ( training set )   in the testing set , 55 patients ( among 62 patients ) with complete clinical data included 
 10 ( 18.2% ) dl+ patients and 45 dl patients . all these patients were classified 
 according to their number of independent risk factors for a dl+ status : 26 had no risk 
 factors , 17 had only one risk factor and 2 had two risk factors . when the patients were 
 divided into groups by those with no risk factors and those with at least one risk factor , 
 the sensitivity and positive predictive value ( ppv ) for detecting intra - abdominal 
 metastasis were 90.0% and 32.1% , respectively . when the patients were divided into groups 
 by those with no risk factors or only one risk factor and those with two risk factors , the 
 sensitivity and ppv were 40.0% and 66.7% , respectively ( table 4 ) . indications for diagnostic laparoscopy based on the number of independent risk 
 factors ( testing set ) ( % ) from september 2011 to september 2013 , 249 patients with histologically confirmed gastric 
 carcinoma underwent diagnostic laparoscopy with peritoneal cytology examination as a 
 routine pretreatment workup , 70.7% of whom are males , with a median age of 57.6 ( range : 
 2981 ) years . on the basis of ct and eus findings , 13 ( 5.2% ) patients were found to 
 have clinical stage i disease , 64 ( 25.7% ) were stage ii disease , and 172 ( 69.1% ) were 
 stage iii disease . for t stage , 15 ( 6.0% ) patients were t2 , 65 ( 26.1% ) were t3 and 169 
 ( 67.9% ) were t4 . as for n stage , 53 ( 21.3% ) patients were n0 , and 196 ( 78.7% ) were n+ . from the diagnostic laparoscopy findings , 14 ( 5.6% ) of the 249 patients had visible 
 peritoneal dissemination only , which was confirmed by frozen pathology , 17 ( 6.8% ) had free 
 cancer cells in the peritoneal lavage only and 20 ( 8.0% ) had both metastases . in total , 51 
 ( 20.5% ) patients were dl+ and 198 were dl. among the dl+ patients , 42 underwent 
 hyperthermic intraperitoneal chemotherapy ( hipec ) followed by palliative chemotherapy 
 after diagnostic laparoscopy , and 9 underwent palliative surgery . among the dl 
 patients , 101 underwent radical d2 gastrectomy , and 97 underwent neoadjuvant 
 chemotherapy . the split sample method was used , and the 249 patients were divided into two sets using 
 random sampling : 3/4 ( 187 patients ) as a training set for developing predictive factors of 
 metastasis and 1/4 ( 62 patients ) as a testing set for validating these factors . the clinical characteristics were compared between the dl+ and dl patients 
 ( table 1 ) . in the training 
 set , 38 ( 20.3% ) patients were dl+ , and 149 patients were dl. ca72 - 4 expression , 
 proportion of the tumor in relation to the circumference of the stomach , tumor - occupied 
 stomach portions , borrmann type , depth of tumor invasion on ct and depth of tumor invasion 
 on eus were found to be significant in our univariate analyses . next , all these factors 
 were evaluated by multivariate analysis . among these factors , multivariate analysis 
 indicated that the depth of tumor invasion on ct scan and tumor - occupied stomach portions 
 are predictive factors of metastasis ( table 
 2 ) . clinicopathologic features of dl+ and dl patients ( univariate analysis , 
 training set )   predictive factors of metastasis ( multivariate analysis , training set )   from an roc curve ( figure 4 , 5 and table 3 ) , the highest youden index ( 0.217 and 0.270 , 
 respectively ) was obtained when the depth of tumor invasion on ct was cut off at 21 mm 
 ( auc : 0.668 , p<0.01 ) and tumor - occupying portions of the stomach were cut off between 
 1 and 2 ( auc : 0.676 , p<0.01 ) . roc for the prediction of intra - abdominal metastasis by the depth of tumor invasion 
 found by ct scans . roc for the prediction of intra - abdominal metastasis by the tumor occupying portions 
 of stomach . prediction of intra - abdominal metastasis by the depth of tumor invasion found by ct 
 scans and the tumor - occupied portions of stomach ( training set )   in the testing set , 55 patients ( among 62 patients ) with complete clinical data included 
 10 ( 18.2% ) dl+ patients and 45 dl patients . all these patients were classified 
 according to their number of independent risk factors for a dl+ status : 26 had no risk 
 factors , 17 had only one risk factor and 2 had two risk factors . when the patients were 
 divided into groups by those with no risk factors and those with at least one risk factor , 
 the sensitivity and positive predictive value ( ppv ) for detecting intra - abdominal 
 metastasis were 90.0% and 32.1% , respectively . when the patients were divided into groups 
 by those with no risk factors or only one risk factor and those with two risk factors , the 
 sensitivity and ppv were 40.0% and 66.7% , respectively ( table 4 ) . indications for diagnostic laparoscopy based on the number of independent risk 
 factors ( testing set ) ( % ) the highest rates of gastric cancer in the world occur in eastern asia , and china accounts 
 for approximately 40% of the worldwide gastric cancer burden . thus , the accuracy of 
 clinical staging is crucial . in the present study , 20.5% of cm0 gastric cancer patients were 
 identified to have peritoneal dissemination or free cancer cells by diagnostic laparoscopy . this finding suggests that pretherapeutic diagnostic laparoscopy with cytology examination 
 should be strongly recommended for gastric cancer patients , especially those with related 
 risk factors . 10 ) performed 
 diagnostic laparoscopy on 657 patients with minimal symptoms and no definite m1 disease , and 
 m1 disease was detected in 23% of patients with this method . in this study , only 65 patients 
 were examined by high - quality spiral ct scans for staging . although all the patients were 
 examined by high - quality spiral ct scans in our study , the metastasis detection rate was not 
 much different . therefore , diagnostic laparoscopy can not be replaced by high - quality imaging 
 techniques . kaiser et al . ( 11 - 13 ) also reported similar metastasis detection rates for 
 resectable m0 gastric cancer patients ( 20.6% , 24.7% and 23.0% , respectively ) . it is widely 
 accepted that peritoneal dissemination spreads from the tumor to the serosa , but in our 51 
 dl+ patients , we also found 2 ct2n0 patients who had free cancer cells , 3 ct3n0 patients who 
 had free cancer cells and 2 ct3n0 patients who had visible peritoneal dissemination . ( 13 ) reviewed patients who underwent 
 diagnostic laparoscopy and laparotomy in the same period , respectively , and showed that 
 there was no significant difference in the rate of intra - abdominal metastasis ( 45.2% 
 vs. 35.5% , p=0.299 ; 20.6% vs. 20.8% , p=0.977 ) . ( 15 ) demonstrated that the 
 collection of peritoneal lavage fluid for cytology during laparoscopy has the same value as 
 its collection during laparotomy . osorio et al . ( 13 ) compared the results of patients who underwent either diagnostic 
 laparoscopy or laparotomy and were not submitted to any additional surgical procedure due to 
 intra - abdominal spread . the patients who underwent diagnostic laparoscopy had a lower 
 morbidity ( 11.8% vs. 50.0% ) , lower mortality ( 0% vs. 
 16.7% ) , shorter hospital stay ( 6.3 d vs. 15.3 d ) , greater chance for 
 recovery until fit for chemotherapy ( 64.7% vs. 33.3% ) and longer survival 
 ( 11.6 months vs. 4.8 months ) . consequently , diagnostic laparoscopy and 
 laparotomy exploration have similar contributions to the assessment of intra - abdominal 
 metastasis and peritoneal lavage cytology . however , in diagnostic laparoscopy , the entire 
 abdominal cavity can be magnified and easily accessed . thus , it is easier to find any tiny 
 peritoneal nodules that are located in the subphrenic space or pouch of douglas , areas that 
 are difficult to evaluate even by laparotomy . however , a low detection rate is a problem for diagnostic laparoscopy . from our present 
 results , almost 80% of cases researchers 
 are trying to identify proper indications to narrow the potential candidates for diagnostic 
 laparoscopy . 10 ) 
 reported that tumor location [ gastroesophageal junction ( gej ) or whole stomach ] and a 
 lymphadenopathy of 1 cm were independent , significant risk factors for m1 , and m1 was not 
 detected in any patient with neither risk factor . ( 14 ) reported that tumor location involving three stomach 
 portions ; macroscopic types 3 , 4 or 5 ; and positive lymph node metastasis to all three 
 factors are significantly correlated with either peritoneal metastasis or positive cytology . our study also found similar risk factors : tumor - occupied 2 portions of stomach and depth 
 of tumor invasion on ct 21 mm ( measurements of stomach wall thickness were made when the 
 stomach was well distended during the ct scan ) . ( 16 ) also showed similar results in their study of 236 
 gastric cancer patients . in our testing set , only one m1 disease was detected in patients 
 with neither risk factor . for the patients who had at least one of these two identified 
 independent risk factors , the sensitivity , ppv and negative predictive value were 90.0% , 
 32.1% and 96.3% , respectively . according to these results , if we performed diagnostic 
 laparoscopy with cytology examination for the selected patients according to the risk 
 factors , the detection rate would be increased by up to 10% , and only approximately 2% of 
 patients would be missed in preoperative diagnosis of intra - abdominal metastases . however , 
 we continue to recommend diagnostic laparoscopy with cytology examination for all advanced 
 gastric cancer patients . another critical problem is the lack of an accepted treatment protocol after diagnostic 
 laparoscopy . we now have a multimodal therapy plan that includes neoadjuvant chemotherapy , 
 neoadjuvant chemoradiotherapy and hipec . therefore , the request for improvement in the 
 accuracy of treatment has been met . in our study , we chose hipec and systemic chemotherapy 
 to treat the patients with peritoneal dissemination or free cancer cells in the peritoneal 
 lavage . seven of the 10 patients showed a negative metastasis after this preoperative 
 treatment and then underwent gastrectomy . nakagawa et al . ( 17 ) reported that preoperative chemotherapy induced the 
 downstaging of gastric cancer in 11 ( 61.1% ) of the 18 patients in their study , with positive 
 cytology from diagnostic laparoscopy . several studies ( 17 - 19 ) used diagnostic laparoscopy as a 
 staging procedure prior to considering patients for neoadjuvant chemotherapy or 
 chemoradiation . the selection of patients , proper treatment regimens , combination treatments 
 with or without intraperitoneal chemotherapy and the type of surgery after chemotherapy 
 remain controversial . cytoreductive surgery ( crs ) and hipec are indicated for gastric cancer 
 with peritoneal disease that is completely or significantly resectable ( 20 ) . staging laparoscopy is very useful in detecting 
 unsuspected peritoneal seeding and in differentiating between localized peritoneal seeding 
 and disseminated carcinomatosis . in japan and korea , crs and hipec are used with palliative 
 or curative intent and for prophylactic treatment in gastric cancer patients ( 21 ) . however , the treatment of carcinomatosis from 
 gastric cancer by peritonectomy and hipec has globally demonstrated worse long - term results 
 than the treatment of peritoneal carcinomatosis from other cancers ( 22 ) . our preliminary data suggest that diagnostic laparoscopy is necessary for the clinical 
 diagnosis of gastric cancer patients . depth of tumor invasion and tumor - occupied portions of 
 stomach are predictive factors of intra - abdominal metastasis . this work was supported by grants supporting the research program of early diagnosis , 
 standardized treatment and therapy effect evaluation of gastric cancer ( no .
objectivediagnostic laparoscopy is recommended for the pretherapeutic staging of gastric cancer 
 to detect any unexpected or unconfirmed intra - abdominal metastasis . 
 the aim of this 
 study was to evaluate the role and indications of diagnostic laparoscopy in the 
 detection of intra - abdominal metastasis.methodsstandard diagnostic laparoscopy with peritoneal cytology examination was performed 
 prospectively on patients who were clinically diagnosed with primary local advanced 
 gastric cancer ( ct2m0 ) . 
 we calculated the rate of intra - abdominal metastases identified 
 by diagnostic laparoscopy , and examined the relationship between peritoneal 
 dissemination ( p ) and cytology results ( cy ) . 
 split - sample method was applied to find 
 clinical risk factors for intra - abdominal metastasis . 
 multivariate logistic regression 
 analysis and receiver - operator characteristic ( roc ) analysis were performed in training 
 set to find out risk factors of intra - abdominal metastasis , and then validate it in 
 testing set.resultsout of 249 cm0 patients , 51 ( 20.5% ) patients with intra - abdominal metastasis were 
 identified by diagnostic laparoscopy , including 20 ( 8.0% ) p1cy1 , 17 ( 6.8% ) p0cy1 and 14 
 ( 5.6% ) p1cy0 patients . in the training set , 
 multivariate logistic regression analysis 
 and roc analysis showed that the depth of tumor invasion on computer tomography ( ct ) 
 scan 21 mm and tumor - occupied 2 portions of stomach are predictive factors of 
 metastasis . in the testing set , when diagnostic laparoscopy was performed on patients 
 who had one or two of these risk factors , the sensitivity and positive predictive value 
 for detecting intra - abdominal metastasis were 90.0% and 32.1% , respectively.conclusionsaccording to our results , depth of tumor invasion and tumor - occupied portions of 
 stomach are predictive factors of intra - abdominal metastasis .