However, it is worth noting that our analysis showed an association between prolactin levels and breast cancer (IVW, OR = 1.058, 95% CI [1.009,1.109], P = 0.02) and ER-positive breast cancer (IVW, OR = 1.066, 95 % CI[1.007,1.128], P = 0.027), with higher prolactin levels increasing the risk of breast cancer and ER-positive breast cancer. Here, PRL is linked to breast cancer.