This news video segment discusses the link between breast cancer and the use of body lotions.
The point is that many commercial hand and body lotions contain various forms of the hormone estrogen. The skin is highly absorbant and the largest organ in the body. These absorbed estrogens have a powerful effect on metabolism and breast fat and glands are highly metabolic tissue.
Dr. Ashton also mentions the prevalance of environmental toxins. Heavy metals, volatile chemicals, plastics, etc. are rampant in the air, soil, and water. Everything we eat, breathe, and drink contains these toxins. Many toxins don't have a metabolic pathway for excretion and therefore get stored in joints and fat. The breast is mostly fat and very susceptible to environmental toxins and excess estrogens.
Dr. Ashton invokes the ayurvedic (Indian medicine) principal which says if something is not edible then don't put it on the skin. She suggests simply rubbing in sunflower, olive, or other natural oils.
My suggestion in addition to this very good idea is to stay well hydrated by drinking 64-80 oz of water and day and making sure to ingest these same oils. In this way you'll moisturize the skin from the inside out. Another important point is to use extra virgin oils or cold pressed oils in dark glass bottles.