The association between the recurrence of solitary non-muscle invasive bladder cancer and tumor infiltrating lymphocytes

AIM: To evaluate whether tumor infiltrating lymphocytes (TIL) in biopsy specimens are associated with the clinical outcome of non-muscle invasive bladder cancer. METHODS: We retrieved tumor specimens from 115 patients with solitary papillary non-muscle invasive bladder cancer treated between 1996 and 2006 and constructed tissue microarrays. Patients were divided in two groups: those with recurrent disease (N = 69) and those without recurrent disease (N = 46) during the follow up of minimum 5 years. All patients were treated with initial transurethral resection and none received adjuvant therapy. Immunhistochemical staining was performed with anti-CD3, CD4, CD8, and Granzyme B (GrB). The CD4+:CD8+ and GrB+:CD8 ratios were determined. RESULTS: Tumor infiltrating lymphocytes were predominantly observed within cancer stroma, and only rare individual cells were observed intraepithelially. The group without recurrent disease had lower levels of CD3+ and CD8+ lymphocytes than the group with recurrent disease (P = 0.0001, P = 0.0002, respectively). The CD4+:GrB+ and GrB+:CD8+ ratios were significantly higher in patients without recurrent disease (P = 0.0002, P = 0.039, respectively). CONCLUSION: This study revealed a possible connection between TIL number and bladder cancer recurrence. TIL subset ratio showed different patterns in recurrent and non-recurrent tumors, which is why it could become a useful a prognostic clinical index if our findings are confirmed in randomized trials.