CD68- and CD163-positive tumor-associated macrophages in renal clear cell carcinoma

This study aimed to analyze the infiltration of tumor-associated macrophages (TAMs) in clear cell renal cell carcinoma (ccRCC) and to assess their Prognostic significance. This study involved a Cohort of 106 patients with ccRCC who underwent partial or radical nephrectomy. Immunohistochemistry (IHC) was employed to assess the expression of two distinct types of macrophages at various tissue locations. The diagnostic utility of CD68-positive (CD68⁺) and CD163-positive (CD163⁺) macrophages was determined via Kaplan-Meier with log-rank tests and Multivariable Cox regression. Compared with those in adjacent tissues, the numbers of CD68⁺ and CD163⁺ TAMs were significantly elevated in ccRCC tissues. Kaplan-Meier analysis demonstrated that high CD163⁺ TAM density was significantly associated with poorer overall survival (p = 0.006 in tumor nest, p = 0.043 in stroma), while CD68⁺ TAMs showed no significant prognostic value (p > 0.4 for all comparisons). Multivariable Cox regression confirmed CD163⁺ TAMs as independent prognostic factors after adjusting for tumor size and histological grade, with particularly strong association in tumor stroma (adjusted HR = 7.22, 95% CI 1.06-25.54, p = 0.003) compared to tumor nests (adjusted HR = 3.56, 95% CI 1.03-15.56, p = 0.045). TAMs, particularly the M2 subtype (CD163⁺), are identified as adverse prognostic factors for ccRCC patients. Those with a high density of M2 macrophages tend to have a poorer prognosis.