Dear Alicia, I have also had experiences with friends of mine who have had breast cancer and then were advised to not breastfeed. I am a lactational physiologist, and have done serious literature searches to see if anyone has done a proper study to look at the ability to breastfeed after breast cancer. There is not a single experimental or epidemiologic study published on this to my knowledge. In regard to your specific question about steroids during lactation, it is well known that lactation (on a population basis) serves as the world's most important contraceptive. A good review of this is an article by Peter Howie called "Natural regulation of fertility." It is published in the British Medical Bulletin, vol. 49, pp. 182-199. Clearly, ovulation (and hence estrogen) is much more likely to occur sooner in women who choose to not breastfeed their infants. In regard to the question concerning the protective effect of breastfeeding on the risk of breast cancer... A most recent very good study concerning this is of the epidemiologic nature. It is by Polly Newcomb et al., and is published in the New England Journal of Medicine, vol. 330, pp. 81-7. This is a retrospective, epidemiologic study that found that the risk of premenopausal breast cancer is reduced by approximately 22% when a woman has breastfed an infant. Interestingly, this effect was the greatest when the woman breastfed an infant before she was 20 yrs (risk was reduced by 50%). Many other epidemiologic studies have been done, and are sited in this article. Hope this helps. Shelley McGuire, Ph.D. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Shelley McGuire Animal and Vet. Science University of Idaho Moscow, ID 83844 (208) 885-6351 FAX: 208-885-6420 "Life itself is the proper binge." -Julia Child, chef +++++++++++++++++++++++++++++++++++++++++++++++++++++