systemic interleukin-6 response after intravesical instillation of bacillus calmette-guérin and mitomycin c in superficial bladder cancer

interleukin-6 (il-6) is proposed to play a significant role in pathogenesis of urinary bladder cancer (ubc). this role may be influenced by chemotherapy (mitomycin c; mmc) or immunotherapy (bacillus calmette-guérin; bcg). a case-control study was conducted to determine il-6 levels in serum of newly diagnosed cases (ndc) of superficial ubc, as well as in patients treated with mmc or bcg intravesical instillation. a total sample of 111 patients (36 ndc, 45 mmc and 30 bcg) was included, as well as a control group of 107 healthy controls (hc). il-6 was detected by enzyme-linked immunosorbent assay. results revealed that median levels of il-6 were significantly elevated in ndc group (15.8 pg/ml; p 0.001) compared to mmc and bcg groups (7.5 and 5.3 pg/ml, respectively) or hc (4.4 pg/ml); while, there were no significant differences between the latter three groups (mmc, bcg and hc). receiver operating characteristic curve analysis revealed that il-6 is a very good predictor of ubc in ndc group versus hc (area under the curve=0.885; 95% confidence interval=0.828-0.942; p 0.001; cut-off value=10.5 pg/ml; youden index=0.62; sensitivity=80.6%; specificity=81.3%). logistic regression analysis confirmed this significance and il-6 was associated with a higher risk of ubc (odds ratio=1.18; 95% confidence interval=1.11-1.26; p 0.001). in conclusion, this study indicated that il-6 level was upregulated in serum of ndc of ubc. further, il-6 level was restored to normal levels after intravesical instillation of mmc or bcg.