Fig. 4

Prognostic significance of the spatial proximity of CD8⁺ cells to cancer cells in pancreatic ductal adenocarcinoma. The distance between the nuclear centers of a KRT7⁺ tumor cell and its nearest CD8⁺ cell was calculated for each KRT7⁺ cell identified within the tumor center of pancreatic cancer (a). A scatter plot shows a strong inverse correlation of the mean distance from tumor cells to the nearest CD8⁺ cells with CD8⁺ cell density (b). CD8⁺ cells adjacent (e.g., r ≤ 20 μm) or not adjacent (e.g., r > 20 μm) to tumor cells were extracted from fluorescent images (c) and were assessed for the prognostic association with pancreatic cancer-specific survival (d). Hazard ratios with 95% confidence intervals for the highest (vs lowest) quartile of the densities of CD8⁺ cells within various distances from tumor cells are explored. P_trend values were calculated across the ordinal quartile categories of CD8⁺ cell density (1–4) as a continuous variable in the Cox regression models