Comparison of tumor microenvironments between primary tumors and brain metastases in patients with non-small cell lung cancer.

Abstract Introduction The present study investigates the immune profile of the primary lung tumors and the corresponding brain metastasis from non-small cell lung cancer patients using multiplex fluorescence immunohistochemistry. Methods The study evaluated 34 patients who underwent autopsy or surgical resection for brain metastasis and autopsy, surgical resection or core biopsy for primary lung cancer. We compared the densities of various immune cells in the primary tumors and the brain metastases by multiplex fluorescence immunohistochemical analysis. Results The density of CD4＋ T cells, CD8＋ T cells, and CD4＋Foxp3＋ T cells were statistically higher in both tumor and stromal areas in primary lung cancer specimens when compared to brain metastases samples (p Conclusions Our findings that CD204+ cells were higher in the brain metastases may have broader implications for treatment as these macrophages may be immunosuppressive and make the immune environment less reactive. Furthermore, the finding that the density of CD4+ T cells was higher in the cancer and stroma areas of brain metastases after radiotherapy supports the addition of immunotherapy to radiation therapy in the treatment of brain metastases in NSCLC.