Evaluation of tumor-associated macrophages as a prognostic indicator in patients with papillary renal cell carcinoma.

Abstract

372 Background: Prognostic indicators in papillary renal cell carcinoma (PRCC) are not well defined. We evaluated the prognostic relevance of tumor-associated macrophages (TAM) in patients with PRCC. Methods: PRCC specimens were re-evaluated by one blinded pathologist (SM), with respect to pT-classification (TNM 2002), nodal status, Fuhrman grade (I-IV), tumor size, subtype (type 1 or 2), tumor necrosis, and presence of TAM. Presence of TAM was associated with pathological parameters (chi-square and fisher's exact tests). Impact of TAM on cancer-specific survival (CSS) was assessed (Kaplan-Meier method and log-rank test). A multivariate regression analysis including pT-stage, grade, vascular invasion, necrosis, tumor size, papillary subtype and TAM was performed with respect to CSS. Results: 177 patients operated for PRCC from 1984 to 2006, were evaluated. Presence of TAM was noted in 112/177 (63%) tumors and was significantly associated with favorable pathological parameters: low pT-classification (pT1a/b: 71/90, 79%; pT2: 14/31, 45%; pT3a/b: 27/56, 48%; p<0.001), node negative tumors (Nx/pN0: 111/170, 65% vs. pN1/2: 1/7, 14%; p=0.01), low grade (G1: 35/45, 78%; G2: 67/110, 61%; G3: 10/22, 45%; p=0.025), absence of vascular invasion (V0: 106/153, 69% vs. V1/2: 6/24, 25%; p<0.001), and papillary subtype (type 1: 64/87, 74% vs. 48/89, 54%; p=0.007), respectively. Median follow-up was 68.3 months. Five-year CSS probabilities for patients with TAM-positive tumors were 93.5%, compared with 72.5% in patients with TAM-negative tumors (p<0.001). Median survival was not reached in both groups. Multivariate analysis revealed node positive tumors (HR=2.4, 95%CI=1.1-5.0; p=0.025), distant metastases (HR=8.7, 95%CI=2.6-29.3; p<0.001), and tumor size (HR=1.2, 95%CI=1.0-1.3; p=0.03) as independent predictors of death from PRCC, whereas presence of TAM was independently associated with favorable outcome (HR=0.3, 95%CI=0.1-0.9, p=0.026). Conclusions: Presence of TAM was independently associated with a favorable outcome in patients with PRCC and was shown to reduce the risk of death from cancer by 66%. Presence of TAM should therefore be part of routine pathology reporting in PRCC. No significant financial relationships to disclose.