Association of stromal lymphocyte infiltration with tumor invasion depth and high-grade T1 bladder cancer.

Abstract

488 Background: Morphological assessment of tumor-infiltrating lymphocytes (TIL) has been shown to provide prognostic and potentially predictive significance in many different tumor types. Large studies investigating TIL in urothelial carcinoma are lacking. We investigated in a homogenous population of patients with high-grade T1 (HGT1) bladder cancer the association of TIL with clinico-pathological parameters and clinical outcomes. Methods: Pretreatment index tumors were collected between 2000 and 2015 from 147 patients with primary high-grade cT1N0M0 bladder cancer. The density of stromal TIL was evaluated using hematoxylin and eosin (H&E)-based staining on whole tissue sections. Stromal TIL density was scored as percentage of stromal area infiltrated by mononuclear cells. Inter-reader assessment and stromal TIL correlation with a subset of CD3+ stained sections were evaluated. The main endpoint was correlation with overall survival (OS). Hazard ratios (HRs) and 95% CIs associated with stromal TIL were estimated through a multivariable Cox model. Results: Median follow-up was 8.2 years (6.1-9.5). Induction BCG therapy was followed by 126 patients (86%). Recurrence and progression were respectively observed in 67 patients (46%) and 40 patients (27%). Stromal TIL density was high (≥10%) in 82 tumors (56%). The overall agreement was good between the two readers (κ = 0.75). Correlation between stromal TIL density analyzed on H&E-sections and CD3+ IHC staining was high (ρ = 0.71, p < 1.10-5). Stromal TIL were positively associated with variant histology (p = 0.01) and tumor invasion depth (p = 0.03). For the OS analysis, intense (≥10%) vs. non-intense ( < 10%) stromal TIL unadjusted HR (95% CI, p) was 1.30 (0.75-2.24, p = 0.34) and adjusted HR was 1.25 (0.72-2.16, p = 0.43). Conclusions: Density of stromal TIL was associated with tumor invasion depth and variant histology, but not with prognosis of patients with HGT1 bladder cancer. These data suggest that tumor progression is associated with an increased adaptive immune response but other factors may influence outcome of patients. Characterization of TIL subpopulations may be required to identify immune-related prognostic factors.