Objective: This study aims to elucidate the impact of repeated whole-body computed tomography (CT) scans on systemic immunity, the tumor immune microenvironment, and tumor control. This inquiry was prompted by clinical observations indicating a decrease in the levels of IFN-β and IFN-γ in patients' blood following whole-body CT scans.
Methods: A Lewis lung carcinoma (LLC) xenograft mouse model was established and divided into two groups: a control group and a group subjected to multiple whole-body CT scanning radiation (WBCTSs). The study monitored tumor growth trends across both groups and employed a comprehensive set of analytical techniques—including enzyme-linked immunosorbent assay (ELISA), flow cytometry analysis, immunohistochemistry, RNA sequencing, and single-cell sequencing—to assess differences in cytokine profiles (IFN-β and IFN-γ), proportions of key immune cells, and gene expression variations between the groups.
Results: Repeated CT scan radiation demonstrated a trend toward delaying tumor progression. In tumors exposed to multiple CT scans, there was an observed increase in the proportion of CD8+ T cells and an upregulation of genes associated with IFNγ in CD8+ T cells and IFN-β in macrophages. Concurrently, interferon levels within the tumor tissue also showed an increase.Conversely, the radiation from multiple whole-body CT scans resulted in a decreased proportion of CD8+ T cells in the blood and spleen, accompanied by a downregulation of genes associated with IFNγ in CD8+ T cells and IFN-β in macrophages, as well as a reduction in serum interferon levels.
Conclusion: Our results suggest that repeated whole-body CT scanning radiation induces systemic immunosuppression as well as immune activation in tumor tissue. Multiple CT scans do not exacerbate cancer, but rather may act as a barrier to cancer progression.
