Peppas I, George G, Sollie S, et al. - Researchers assessed the link of serum immunoglobulin classes with solid cancer in this systematic review and meta-analysis, as well as, they investigated whether the immune escape of tumors is accompanied by dysregulated systemic immunoglobulin class-switching. Observational investigations examining the link between serum immunoglobulins (IgA, IgG, and IgM) and histologically verified diagnosis of solid cancer in adults were identified from Cochrane Library, Embase, and MEDLINE/PubMed databases. The standardized mean difference (SMD) with 95% confidence intervals, estimated utilizing a random effects model, was the primary summary measure. A statistically significant SMD was identified by pooling 11 eligible studies that compared serum IgA levels among 1,351 patients and 560 controls. For the 14 elected studies examining serum IgG and for the 10 studies describing serum IgM, they found nonsignificant SMDs. Among patients diagnosed with solid cancer, the possible skewing of serum immunoglobulin levels toward class-switching to IgA was suggested, which likely indicates Th2-polarized immunity.