To investigate the association between p53 expression in tumor cells and intratumoral macrophage infiltration in muscle-invasive urinary bladder cancer (MIBC) in relation to clinical and pathological variables and outcomes after radical cystectomy.

Tumor specimens of the primary tumor from patients treated with radical cystectomy for MIBC were immunostained with the M2-macrophage-specific marker CD163 and the cell cycle protein p53. The expression of these markers was analyzed in relation to patients´ and tumor characteristics and outcome.

Out of 100 patients with urinary bladder cancer (UBC) pathological stage T1-4 N0-3 M0, 77% were men. The patients had a median age of 69 years and 80% had nonorgan-confined tumors (pT3-4). Lymph node metastasis was found in 42 (42%) of all patients. P53-positive expressions were found in 63 (63%) patients. Strong macrophage infiltration in the tumor microenvironment was shown in 74 (74%) patients. Combinations of CD163/p53 status were as follows: CD163+/p53+, 50%; CD163+/p53-, 24%; CD163-/p53+, 13%; and CD163-/p53-, 13%. Patients with CD163+/P53+ had higher proportions of organ-confined tumors.

In the present series of patients with MIBC treated with cystectomy, we found that high CD163+ macrophage infiltration in the tumor micro-environment often was combined with p53+ cancer cells. This simultaneous expression of p53 by tumor cells and increased infiltration of M2-macrophages in the tumor microenvironment was associated with improved CSS, which might indicate a possible protective effect of M2 macrophages in p53+ tumors. Further investigations are needed to explore the biological relation between mutational burden and immune profile in MIBC.