Tumour‐associated macrophages might represent a favourable prognostic indicator in patients with papillary renal cell carcinoma

Aims Tumour‐associated macrophages ( TAM ) have been reported to be regulators of progression in various human cancers. We evaluated the prognostic relevance of TAM in a large series of patients with papillary renal cell carcinoma ( PRCC ). Methods and results The impact of TAM on cancer‐specific survival ( CSS ) in 177 patients with PRCC was assessed using the K aplan– M eier method and log‐rank test. A multivariate C ox regression analysis was performed with respect to CSS . The presence of TAM was noted in 112 of 177 (63%) tumours and was associated statistically significantly with favourable pathological parameters, including low pathological T stage, node‐negative tumours, low tumour grade, absence of vascular invasion and papillary subtype (all P  <   0.05), respectively. Five‐year CSS probabilities for patients with TAM ‐positive tumours were 93.5%, compared with 72.5% in patients with TAM ‐negative tumours, respectively ( P  <   0.001). Multivariate analysis revealed node‐positive tumours, distant metastases and UICC stage (I versus II – IV ) as independent predictors of death from PRCC , whereas the presence of TAM was associated independently with favourable outcome (hazard ratio = 0.45, 95% confidence interval 0.24–0.84, P  =   0.012). Conclusions The presence of TAM was shown independently to reduce the risk of death from cancer by 55%. The presence of TAM should therefore become part of routine pathology reporting in PRCC .