***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: OBJECTIVES : Difficult diagnoses and a lack of effective therapy complicate biliary tract malignancies .  Interleukin-6 ( IL-6 ) is a human bile duct epithelium growth factor correlated with tumor burden . We evaluated the usefulness of serum IL-6 in the diagnosis of primary BDC and measured changes in serum IL-6 levels following photodynamic therapy ( PDT ) . METHODS : We prospect ively measured serum IL-6 levels in patients with BDC ( N = 26 : 14 patients treated with PDT , 12 with biliary drainage alone ) , hepatocelluar carcinoma ( HCC , N = 26 ) , and healthy adults ( N = 23 ) .  Serum IL-6 levels were measured by an enzyme-linked immunosorbent assay . Patients with clinical conditions known to increase IL-6 levels were excluded . RESULTS : IL-6 was detected in all patients with BDC and HCC , and in 6 of 23 healthy adults .  Median and mean levels of IL-6 were higher in patients with BDC than in both other groups ( P < 0.001 ) . Using a 25.8 pg/mL cutoff , IL-6 provided a diagnostic sensitivity of 73 % and a specificity of 92 % ; positive and negative predictive values were 83 % and 87 % , respectively . Serum levels of IL-6 were correlated with tumor burden in BDC patients . One month after treatment of BDC with PDT , the mean IL-6 level decreased significantly from 282.1 ± 121.8 to 38.2 ± 9.9 pg/mL ( P = 0.008 ) . CONCLUSIONS : Serum IL-6 concentration is a useful addition to the available tests for the differential diagnosis of BDC , and serves as a marker for monitoring the response to treatment of BDC with PDT AIM Serum alpha-fetoprotein  ( AFP ) is the most important tumor marker for hepatocellular carcinoma ( HCC ) . Previous reports indicated that HCC was also associated with increased levels of interleukin (IL)-6 , IL-10 and hepatocyte growth factor ( HGF ) . This study investigated the role of these cytokines as tumor markers for HCC . METHOD A total of 128 adults were prospect ively enrolled and categorized into four groups : normal subjects ( n=29 ) , chronic hepatitis B or C ( n=50 ) , non-HCC tumors ( n=23 ) and HCC ( n=26 ) .  Serum AFP , IL-6 , IL-10 and HGF levels were determined in all subjects . RESULTS The expression of IL-6 or IL-10 ( > or =3 pg/ml ) , or high level of HGF ( > 1000 pg/ml ) or AFP ( > 20 ng/ml ) was observed in only 0 - 3 % of normal subjects . Patients with HCC more frequently had higher IL-6 and IL-10 levels ( p<0.05 ) , whereas HGF levels in HCC patients were not significantly elevated compared to patients with chronic hepatitis or non-HCC tumors . Among patients with low ( < 20 ng/ml ) AFP level , IL-6 or IL-10 expression was significantly associated with the existence of HCC ( p<0.05 ) . Patients with large ( > 5 cm ) HCC more often had increased IL-6 , IL-10 or AFP levels ( p values all < 0.05 ) . CONCLUSIONS Serum levels of IL-6 and IL-10 are frequently elevated in patients with HCC but not in benign liver disease or non-HCC tumors . IL-6 and IL-10 may help identify a subset of HCC patients with low AFP level , and may serve as complementary tumor markers in these patients Interleukin-6  ( IL-6 )  is a promising tumor marker for hepatocellular carcinoma ; HCC . IL-6 may help to identify a subset of HCC patients with low alpha-fetoprotein ( AFP ) level , and may serve as complementary tumor marker , however , this has to be clarified . This study assesses the value of measuring serum level of interleukin-6 in patients with chronic liver disease and HCC , and evaluates its sensitivity and specificity in comparison to AFP in early diagnosis of HCC . Seventy five patients with chronic liver disease ( CLD ) with or without HCC and 25 healthy controls were included . Patients were divided into Group I : 25 patients with CLD but no evidence of HCC . Group II : 25 patients with HCC on top of post-viral hepatitic with elevation in AFP ( > 200 ng ) ; and Group III : 25 patients with HCC on top of post-viral hepatitic but without elevation in AFP ( < 200 ng ) . Analysis of the mean serum IL-6 levels revealed a statistically significant difference between all groups ( P < 0.01 ) . A significant positive correlation was found between mean levels of IL- 6 & AFP in HCC ( P < 0.05 ) , the mean IL-6 levels in patients with Child classification C was higher than in those with Child A and B.After adjustment using multiple logistic regressions , only loss of weight and AFP were found to be significantly associated with HCC ( P < 0.05 ) . It is concluded that the diagnostic value of IL-6 increased when it is associated with AFP measurement . Combining the two markers can provide a new perspective in the diagnosis of HCC 
    Output:
    
Conclusions The elevated IL-6 levels in HCC patients compared with hepatitis and cirrhosis patients and healthy controls may show a significant association of this cytokine with increased risk of HCC and its potential as a diagnostic marker for HCC in future diagnostic and therapeutic strategies