In addition, we also found a significant combination of OPRM1 hypermethylation and a high pork intake (≥1 time/week, OR = 3.628, 95%CI: 1.593–8.262, P = 0.000) and high psychological stress index (>15, OR = 5.340, 95%CI: 2.634–10.829, P = 0.000) for increased breast cancer risk. Here, OPRM1 is linked to breast carcinoma.