Serum IL-6 level is associated with clinical outcome of intravesical gemcitabine therapy in T1 non-muscle-invasive bladder cancer.

Abstract

Serum biomarkers are valuable tools to predict the prognosis of anticancer therapies. This study aimed to evaluate the impact of serum interleukin-6 (IL-6) level on the clinical outcome of intravesical gemcitabine (GEM) therapy in non-muscle-invasive bladder cancer (NMIBC). This retrospective study enrolled 71 patients initially diagnosed with T1 NMIBC who underwent intravesical GEM therapy between 2017 and 2019. The expression of IL-6 gene was examined by real-time PCR. Serum IL-6 level was determined by enzyme-linked immunosorbent assay (ELISA). The cell viability after gemcitabine treatment was measured by CCK-8 assay. The optimal serum IL-6 cutoff values for recurrence prediction were calculated using receiver-operating characteristic curve analysis with reference to cancer recurrence. Recurrence-free survival was compared by the log-rank test. Univariate and multivariate Cox regression analysis was conducted to identify the prognostic factors influencing recurrence-free survival after treatment with intravesical GEM. Increased expression and secretion of IL-6 were observed in GEM-resistant sublines compared with parental bladder cancer cell lines. Serum IL-6 level rendered a sensitivity of 82.6% and a specificity of 77.1% to correlate with the cancer recurrence after intravesical GEM. Patients with a high serum IL-6 level exhibited shorter recurrence-free survival after intravesical GEM. Moreover, serum IL-6 level in our NMIBC cohort was significantly associated with clinicopathological characteristics, such as tumor diameter, multifocality, concomitant CIS, and grade. Serum IL-6 level was an independent prognostic factor for recurrence-free survival in NMIBC patients treated with intravesical GEM. Given that it was significantly associated with clinical outcome of intravesical GEM therapy, serum IL-6 level might be used as a potential prognostic biomarker for intravesical GEM in T1 NMIBC.