The clinical implication of gamma globulin levels in patients with nonmuscle-invasive bladder cancer.

OBJECTIVE: The production of antibody, also referred immunoglobulin, is the principal functions of B cells. Gamma globulin fraction determined by serum protein electrophoresis is composed almost entirely of immunoglobulin. This study aimed to investigate the association between gamma globulin level and oncological outcomes in patients with nonmuscle-invasive bladder cancer (NMIBC). PATIENTS AND METHODS: A total of 274 patients with NMIBC who underwent transurethral surgery between 2000 and 2015 were identified. One hundred forty-four patients (52.6%) had received adjuvant intravesical bacillus Calmette-Guérin. Gamma globulin fraction (%) was determined by serum protein electrophoresis, and gamma globulin level (mg/dl) was calculated by multiplying the total protein level (mg/dl) by the gamma globulin fraction (%). The association between gamma globulin levels and oncological outcomes was statistically evaluated. RESULTS: During a median follow-up period of 39 months, 99 (36.1%) patients experienced at least 1 tumor recurrence and 16 (5.8%) patients had disease progression. The median (interquartile range) gamma globulin level was 1.2 (1.0-1.3) mg/dl. Recurrence-free survival rate of patients with gamma globulin levels of ≥1.4 mg/dl was significant lower than that of patients with gamma globulin levels of <1.4 mg/dl (P < 0.01). There was no significant difference in progression-free survival between the 2 groups (P = 0.17). Multivariate analysis revealed that gamma globulin level of ≥1.4 mg/dl is significantly associated with higher recurrence rate (hazard ratio = 1.83, P < 0.01). CONCLUSION: Gamma globulin level is significantly associated with tumor recurrence. Our results suggest that B cell immunity may be involved in tumor recurrence in patients with NMIBC.