Correlation of Cell-in-Cell Structure With Prognosis in Solid Tumors-A Meta-Analysis.

Background: Cell-in-cell structures (CICs), a novel biomarker for complex cellular interactions, have garnered increasing attention for their potential in predicting cancer patient prognosis. However, the prognostic significance of CICs in tumor outcomes remains inconclusive. To address this, we conducted a meta-analysis to assess the prognostic value of CICs in solid tumors, adhering to the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines. Methods: PubMed, Web of Science, and Cochrane Library databases were searched up to October 2024 for the retrieval of full articles. Studies related to the prognosis of cell-in-cell and solid tumors were considered eligible for analysis. The quality of the included studies was assessed according to the National Institute for Health and Clinical Excellence (NICE) Quality assessment tool. Results: We included 1836 patients with solid tumors to evaluate the association between overall cell-in-cell structures (oCICs) and prognosis, and 429 patients to evaluate the association between four subtypes of CICs (tumor-in-tumor [TiT], tumor-in-macrophage [TiM], macrophage-in-tumor [MiT], and lymphocyte-in-tumor [LiT]) and prognosis. We present the hazard ratio (HR) for overall survival (OS) for the number of CICs for each solid tumor. The combined HR for OS of oCICs was 1.64 (95% CI, 1.18-2.28; p = 0.003), and for LiT, it was 1.43 (95% CI, 1.12-1.83; p = 0.005), indicating that both oCICs and LiT are reliable prognostic factors for solid tumors. However, the combined HRs for OS of TiT, TiM, and MiT were 0.72 (95% CI, 0.35-1.48; p = 0.37), 1.28 (95% CI, 0.67-2.45; p = 0.46), and 1.54 (95% CI, 0.93-2.56; p = 0.09), respectively, suggesting that these subtypes may not be reliable prognostic factors due to the limited number of studies. Conclusion: The presence of higher numbers of oCICs and LiT is an adverse prognostic factor for patients and affects OS.