A study conducted by the Dr. Susan Love Research Foundation in conjunction with researchers at the University of California, Los Angeles was recently published in the Journal of Physiology and Biochemistry.
Below you will find a summary of the published paper. You can read the original abstract here.
The physiology of the nonlactating human breast is not well understood. Due to concerns about exposing infants to drugs and toxic chemicals through breast milk, much research has been conducted on the lactating breast. However, similar studies have rarely been conducted on the physiology of the resting (nonlacting) breast. Yet, the physiology of the nonlactating human breast is likely to play a key role in factors that contribute to breast cancer and other breast conditions.
Virtually all breast cancer begins in the breast ducts, which are lined with a small amount of fluid called ductal fluid. It is not understood to what extent carcinogens can get into the ductal fluid and how they might cause the cells in the duct to become cancer cells. We believe that learning more about breast physiology, including the composition of breast ductal fluid, will help us better understand both the normal breast and how breast cancer develops.
Studies of the lactating breast have identified how caffeine, drugs, or other compounds are transported into breast milk, but it is not known whether similar transport processes are at work in the nonlactating breast.
Ductal lavage is a medical procedure that can be used to obtain ductal fluid. The procedure, which can be done in a doctor’s office, involves inserting a small catheter into the ductal openings in the nipple and washing out cells and ductal fluid from inside the duct.
This study used ductal lavage to explore whether certain drugs get into the ductal fluid of nonlactating women and if so, to determine if the concentration of the drugs in the fluid is similar to that observed in the breast milk of lactating women. The two compounds studied, caffeine and cimetidine (Tagamet), were selected because they have both been studied in breast milk. They were also selected because they are known to enter milk in different ways: caffeine passively diffuses into breast milk whereas cimetidine is actively transported and concentrated in breast milk.
There were 14 nonlactating women enrolled in this study. After ingesting caffeine and cimetidine, each woman had her blood drawn and had a ductal lavage procedure five times over a 12 hour time period. This allowed us to measure changes in concentrations of the caffeine and the cimetidine in the fluid and in the blood. In addition, we compared the concentrations of the drugs in the fluid to their concentrations in breast milk, which have been reported in previous studies.
With both caffeine and cimetidine, we found that there were much lower levels of the drugs in the ductal lavage fluid than in either the blood or in breast milk.Â This was in striking contrast to the much higher levels of cimetidine found in breast milk than in the blood. We believe that these results support our hypothesis that mechanisms of molecular transport in the breast differ depending on whether or not lactation is occurring. This is important because understanding how compounds such as drugs and carcinogens get into the nonlactating breast could help us determine how breast cancer starts.
In addition to enhancing our understanding of the physiology of the nonlactating breast, these results have ramifications for the exploration of environmental risk factors for breast cancer. Many studies focus on looking for environmental toxins in breast milk to determine their link to breast cancer. Our study suggests that what is found in breast milk does not necessarily reflect what is happening in the nonlactating breast, and that it might be more informative to examine ductal fluid in nonlactating women than breast milk. Our study also underscores the need for more research on the physiology of the resting, nonlactating breast.
J Physiol Biochem. 2011 Dec;67(4):621-7. Epub 2011 Oct 8.
The physiology of the normal human breast: an exploratory study.
Mills D, Gordon EJ, Casano A, Lahti SM, Nguyen T, Preston A, Tondre J, Wu K, Yanase T, Chan H, Chia D, Esfandiari M, Himmel T, Love SM.