HFD-induced obesity increases tumor growth and decreases immune cell infiltration in mice. (A–D) C57BL/6 mice were fed an HFD (n = 14–16) or an SFD (n = 14–16) for 6–9 wk, and MC38 tumors were injected. Graphs depict weight at 9 wk for HFD (A), tumor volume on day 7 after tumor inoculation (B), and tumor growth progression (C). (D) Tumors from C were dissected, and immune cell infiltration was analyzed by flow cytometry. (E) C57BL/6 mice were fed an HFD or SFD for 10–13 wk, and mice were injected s.c. with B16-F10 tumor cells. Graph indicates tumor volume on day 11 after tumor inoculation from five pooled experiments (SFD, n = 31; HFD, n = 33). (F) Tumors from one experiment in E were dissected, and immune cell infiltration was analyzed by flow cytometry (SFD, n = 6; HFD, n = 7). Data are shown as individual mice (dots) and mean ± SEM. (A, B, D, and E) Unpaired Student’s t test. (C) Two-way ANOVA. *, P < 0.05; **, P < 0.01; ***, P < 0.001. This experiment was performed five times in the MC38 model and six times in the B16 model.