In accordance with Foxp3 expression, a higher frequency of IDO+ cells was observed in SLN of breast cancer patients (median 4.0%, range 2.3–6.0%) when compared to controls (median 1.6%, range 0.8–3.3%), but the difference was not statistically significant, p = 0.08, Figure 2c. This evidence concerns the gene FOXP3 and breast cancer.