This really is an intriguing thread and reminds me so much of my experience, years ago as a leader/rep with La Leche League, an organization helping mothers who want to breastfeed. We often had mothers who came for help with "plugged ducts" (redness, soreness and lump in one area of the breast) and we would relay the medical advisory board info (as well as personal experience) that this was due to (as one doctor noted) an "indiscretion on the part of the mother" i.e. wearing a too tight bra, wearing a bra at night or not completely emptying the breast at each feeding. This type of "irritation" was very simply taken care of by applying heat or standing in the shower with very warm water running over the breast and massaging it downward. Research does indicate that there is less breast cancer among women who breastfeed, but I wonder about the connection between the plugged duct, breast mastitis or breast cancer. Looking forward to more info on this chronic irritation theory.