endometriosis is a progressive disease which consists of implantation of a combination of endometrial tissue including both stromal and glands outside the uterine cavity and may cause pelvic pain , severe intra - peritoneal adhesions and sub - fertility . it is more common in women who complain of chronic pelvic pain , dysmenorrhea and infertility ( 1,2 ) . lack of non - invasive diagnostic methods leads to late diagnosis of endometriosis ( 3 ) . finding a noninvasive and simple method of diagnosis for evaluation of the women who are suspicious for endometriosis is always under serious concern . ca125 is a kind of cell surface antigen which is high in most cases of endometriosis , and has been proposed as a screening method for this disease . however , a meta - analysis on 22 studies , reported a very low diagnostic value for this test . serial measurement of ca125 may help for following up the patients after treatment ( 2 ) . the cytokines including il-6 have been proposed in the pathogenesis of endometriosis ( 4 ) . il-6 which is a multifunctional cytokine has been shown in a very high level in the peritoneal fluid of endometriotic women ( 5 ) . surgery for endometriosis may reduce the level of serum il-6 ; it may decrease after gnrh agonist therapy ( 6 ) . interleukin1 is a responsible cytokine in inflammatory and immunologic responses and is secreted from monocytes , activated macrophages , b and t lymphocytes and nk cells . it has been found in peritoneal fluid of endometriotic women and may cause activation of endometriotic tissue through releasing of angiogenic factors including il6 . in a study in 2002 , il6 was found higher in serum of endometriotic women . in this study ( 4 ) , area under the roc curve of 87% was calculated for serum il-6 . in contrast , some studies could not show diagnostic or prognostic value for serum il6 in endometriotic women ( 5,8 - 12 ) . the purpose of the present study was to compare the serum level of il6 and ca125 in the women with and without endometriosis . morover , they were compared in minimal to mild and moderate to severe cases . this case - control study was performed on women who underwent laparoscopy for their gynecologic problems including tubal ligation , abnormal uterine bleeding , infertility , pelvic pain , and  in rasool - e - akram teaching hospital in tehran , iran , between march 2010 and march 2013 . serum levels of il-6 and ca125 were measured in all women with and without the diagnosis of endometriosis and were compared between these two groups . endometriosis was defined as minimal to mild if it was found on the surface of peritoneum and ovaries without deep and severe adhesions ( 1 ) . endometriosis was defined as moderate to severe if it was invasive , with large endometriomas and deep and extensive adhesion according to afs ( american fertility society classification ) scoring system ( 1 ) . inclusion criteria included women of reproductive age who were the candidate for laparoscopic evaluation of their gynecologic problems . exclusion criteria included women with the diagnosis of acute pelvic inflammatory disease ( pid ) and vaginal discharge , women with any known history of inflammatory disorder or high erythrocyte sedimentation rate ( esr ) , neoplastic disorders , history of fever during past seven days , any medication for endometriosis during the last 3 months , laparoscopic findings of other pathologies except endometriosis in laparoscopy and elevated esr . laparoscopy was performed by two expert laparoscopic surgeons who made the diagnosis and staging of endometriosis . in this study considering  = 0.05 and = 0.1 , or=3 a sample size of 76 women in each group was calculated . seventy six women with confirmed diagnosis of endometriosis in laparoscopy were compared with women who had normal laparoscopic findings . three mlit of peripheral blood was collected in eligible women before laparoscopy and the serum il-6 ( elisa , bender med , canada ) and ca125 ( elexis , roche , germany ) were measured and compared between the groups . 
 
 the obtained data were analyzed using spss 16 . quantitative data was calculated as mean  standard deviation and qualitative data was calculated as numbers and percentages . univariate analysis and chi - square test were utilized for comparing quantitative and qualitative data , respectively . . p - value of less than 0.05 was considered significant . for maximum diagnostic value ( sensitivity of 100% and specificity of 100% ) and corresponding confidence intervals ( ci ) , the area under the roc curve is 1 ; and in the minimum diagnostic value , that the diagnosis is totally by chance , the area under the curve is 0.5 . this case - control study was performed on women who underwent laparoscopy for their gynecologic problems including tubal ligation , abnormal uterine bleeding , infertility , pelvic pain , and  in rasool - e - akram teaching hospital in tehran , iran , between march 2010 and march 2013 . serum levels of il-6 and ca125 were measured in all women with and without the diagnosis of endometriosis and were compared between these two groups . endometriosis was defined as minimal to mild if it was found on the surface of peritoneum and ovaries without deep and severe adhesions ( 1 ) . endometriosis was defined as moderate to severe if it was invasive , with large endometriomas and deep and extensive adhesion according to afs ( american fertility society classification ) scoring system ( 1 ) . inclusion criteria included women of reproductive age who were the candidate for laparoscopic evaluation of their gynecologic problems . exclusion criteria included women with the diagnosis of acute pelvic inflammatory disease ( pid ) and vaginal discharge , women with any known history of inflammatory disorder or high erythrocyte sedimentation rate ( esr ) , neoplastic disorders , history of fever during past seven days , any medication for endometriosis during the last 3 months , laparoscopic findings of other pathologies except endometriosis in laparoscopy and elevated esr . laparoscopy was performed by two expert laparoscopic surgeons who made the diagnosis and staging of endometriosis . in this study considering  = 0.05 and = 0.1 , or=3 a sample size of 76 women in each group was calculated . seventy six women with confirmed diagnosis of endometriosis in laparoscopy were compared with women who had normal laparoscopic findings . three mlit of peripheral blood was collected in eligible women before laparoscopy and the serum il-6 ( elisa , bender med , canada ) and ca125 ( elexis , roche , germany ) were measured and compared between the groups . quantitative data was calculated as mean  standard deviation and qualitative data was calculated as numbers and percentages . univariate analysis and chi - square test were utilized for comparing quantitative and qualitative data , respectively . . p - value of less than 0.05 was considered significant . for maximum diagnostic value ( sensitivity of 100% and specificity of 100% ) and corresponding confidence intervals ( ci ) , the area under the roc curve is 1 ; and in the minimum diagnostic value , that the diagnosis is totally by chance , the area under the curve is 0.5 . a total of 152 women were evaluated by laparoscopy , including 76 women in endometriosis or case group , and 76 women in the control group . mean age , gravidity , body mass index ( bmi ) , and esr did not show significant difference between the two groups ( table 1 ) . table 2 shows chief complaints of women in the each group ; it shows significant difference ( p= 0.001 ) . mean serum levels of il-6 and ca125 were higher in the case group ( table 3 ) . serum level of il-6 was not higher in minimal to mild endometriosis than control group ; however , it was higher in moderate to severe endometriosis ( tables 4 and 5 ) . serum level of ca125 was higher in both minimal to mild and moderate to severe endometriosis than control group ( tables 4 and 5 ) . for a cutoff point of 35 iu / ml for ca125 , sensitivity , specificity , ppv and npv were 44.76% , 94.73% , 89.47% and 63.15% , respectively ( figure 1 ) . for a threshold of 30 pg / ml for il-6 , sensitivity , specificity , ppv and npv were 21.1% , 66.6% , 86.8% and 23.37% , respectively ( fig . 2 and table 6 ) . figure 1 and table 6 show the roc curve of diagnostic value of ca125 for diagnosis of endometriosis with confidence intervals . figure 2 shows the roc curve of value of the il-6 for prediction of endometriosis . in the present study both ca125 and il-6 levels were higher in patients with endometriosis ; however , ca125 level was high in both minimal to mild and mild to moderate endometriosis , and il-6 level was higher just in moderate to severe cases . roc curve showed low diagnostic value for il-6 ; therefore it can not be considered as a suitable diagnostic or prognostic test . il-6 which is a multifunctional cytokine , has been shown in the peritoneal fluid of endometriotic women in a very high level ( 5 ) . surgery for endometriosis may reduce the level of serum il-6 , and it may decrease after gnrh agonist therapy ( 6 ) . in a prospective study on 91 cases of endometriosis ( 4 ) who had been undergone laparoscopy , serum and peritoneal level of il and other cytokines were evaluated . serum level of ca125 was higher in moderate to severe cases of endometriosis compared with minimal to mild cases ( 3 ) . a case - control study on 68 endometriotic women and 70 normal women , reported higher serum level of il-6 in endometriotic women which were in accordance with some other studies ( 6,7 ) . additionally , martinez et al . ( 13 ) in a case - control study on 47 case of endometriosis and 72 normal cases , showed elevated level of il-6 in endometriosis . in contrast , some other studies have questioned the value of serum il-6 for diagnosis of endometriosis with this hypothesis that il-6 was secreted by both ectopic and utopic endometrial stromal cells ( 5,9 ) . on the other hand , some studies could not show higher level of il-6 in endometriosis than normal women ( 11,12 ) ; they proposed that il-6 can not add more information than ca125 for the management of endometriosis ( 10 ) . another study on 13 women could not show significant difference between serum and peritoneal fluid il-6 level in women with deep endometriosis and superficial endometriosis ( 10,12 ) considering controversies between our results and also within previous studies , it is suggested that more studies to be performed on cases with various severities of endometriosis before proposing a definitive conclusion .
background : the purpose of the present study was to compare the serum levels of il6 and ca125 
 in women with and without endometriosis . 
 they were also compared in mild , moderate and severe 
 cases . 
 methods : in this case - control study , ca125 and il6 levels in 76 women with laparoscopic proven 
 endometriosis were compared with 76 women without evidence of endometriosis . 
 sensitivity , specificity , 
 positive ( ppv ) and negative ( npv ) predictive values were then calculated for each test . 
 results : both groups did not show significant difference in their age , bmi , esr and gravidity . 
 mean serum levels of il-6 and ca125 were significantly higher in the case group ( 30.46.43 vs 
 13.93.17 pg / ml and 62.610.69 vs 16.61.79 iu / ml respectively ) . considering a cutoff point of 30 
 pg / ml for il-6 , sensitivity , 
 specifically , ppv and npv value of 21.1% , 66.6% , 86.8% and 23.37% 
 were obtained , respectively . considering a cutoff point of 35 iu / ml for ca125 , sensitivity , specifically , 
 ppv and npv were 44.76% , 94.73% , 89.47% and 63.15% , respectively . 
 area under the roc 
 curve was 0.69 for ca125 and 0.54 for il6 , which showed a low value for these tests . 
 conclusion : although ca125 and il-6 were higher than normal controls in endometriosis , area 
 under the roc curve , did not show significant any diagnostic value for these tests .