FSTL1 and gastric cancer: In this study, we found that (1) FSTL1 was highly expressed and correlated with worse prognosis in GC patients, (2) high expression of FSTL1 was positively correlated with immune infiltration in GC, and (3) high expression of FSTL1 promotes the polarization of M1 macrophages to M2 macrophages in GC.