I don't know about the drug HOWEVER since you have been diagnosed fairly early there may be some familial connection. If your Mother tests positive for the BC gene then you and your Sister likely are also positive. In this case you both should have begun testing much earlier than normal. Of course now this advice is a mute point but you Sister should begin Mammography. As unfortunate as it seems many women in their 30s are diagnosed with BC with or without any family history. Regards ....
As you probably know, DES Daughters are defined as women born between 1938 and 1971 who were exposed to DES before birth (in the womb). Research has confirmed that DES Daughters are at an increased risk for:
Clear cell adenocarcinoma (CCA), a rare kind of vaginal and cervical cancer
Increased risk for clear cell cancer appears to be highest for DES Daughters in their teens and early 20s. However, cases have been reported for DES Daughters in their 30s and 40s (Hatch, 1998).
Reproductive tract structural differences (for example, T-shaped uterus)
Pregnancy complications, such as ectopic (tubal) pregnancy and pre-term delivery
Here is a link to the Center for Disease Control Web site on DES:
There is no mention of breast cancer as a known side effect.
However, as japdip suggested, since you have been dx with BC at such a young age, you may want to consider genetic testing for BRCA 1 and 2, which can be inherited from either side of the family. This could be important information in regard to the level of BC risk for children you may have in the future, as well as for your sister.
After responding to your post in 2010, I later came across a new study which revealed addtional risks to DES daughters. I was unable to find your thread, so I could not update the information I had posted about a year earlier. I am glad to have the opportunity to do that now:
"A 20-year study, published October 2011 in the New England Journal of Medicine, lists 12 known health conditions with direct links to DES exposure. Eight of these are fertility-related, ranging from ectopic pregnancy, to infertility, to miscarriage. Of the remaining four, two are cancers: clear cell adenocarcinoma, a rare vaginal cancer; and breast cancer.
According to the study, breast cancer risk for DES Daughters over the age of 40 is nearly double that of the general population. This means that while all DES daughters are subject to the same “1 in 8 lifetime risk” other women worry about, an additional 1 in 50 will develop breast cancer as a result of their DES exposure."
Lawsuits have been filed on behalf of DES daughters around the country who developed BC as adults. One lawsuit, currently in trial in Boston, is being featured in the news at this time.