This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Congestions and localized hardness and obstruction of mammary ducts are amenable to iodine frictions, but the skin of the breast is very sensitive and easily irritated. I can recommend a weak solution of iodoform (1 in 15 to 30) for many of these mammary growths. In 1871 I ordered it for a lady with a large, suspicious-looking tumor, which was to have been removed the following week under the advice of an eminent surgeon. The growth quickly diminished under the iodoform, and the lady is now (1880) quite well. This is only one of many similar instances which have come under my own observation.