Reduced number of IFN‐γ producing cells in peripheral blood is a biomarker for patients with renal cell carcinoma

Renal cell cancer (RCC) is the most lethal of all the common urologic cancers and constitutes 2.2% of all malignancy diagnoses. The incidence of RCC has been steadily increasing in recent decades. The classic risk factors of RCC include smoking, hypertension, obesity, genetics, and genetic mutations. Recent studies also revealed that RCC was an immunogenic tumor and affected by host immune status. Among the pan‐cance, RCC presented with the highest degree of immune infiltration, indicating RCC patients might benefit from immunotherapy. A new immune classification of RCC has been developed by Su et al. based on tumor‐infiltrating lymphocytes to guide clinical practice. However, these studies mainly focus on biomarkers derived from tumor microenvironment (TME), the biomarkers based on peripheral blood samples to RCC have rarely been described. We collected peripheral blood samples from RCC patients and their matched healthy controls and detected the number of IL‐2 and IFN‐γ producing cells by implementing an enzyme‐linked immunospot (ELISPOT) assay. This is the first study to report blood‐based immune biomarkers for RCC using an ELISPOT assay. Our results suggested the frequency of IFN‐γ producing cells but not IL‐2 producing cells was associated with RCC risk. These findings warrant further validation in larger prospective studies.