Feb 2, 2012 02:54AM - edited Feb 2, 2012 02:56AM by AlaskaAngel
I have more of a question or theory than a conclusion about tamoxifen use for breast cancer, for those here to consider (not only HER2 positives, but HR negatives).
I was dx'd stage 1 grade 3 HER2+++, and after doing CAFx5 and rads, was put on tamoxifen. I was on it for a year and then started finding reliable info on the net in 2003 that indicated that about 1/3 of the HER2 positive bc patients developed resistance to tamoxifen. Since they didn't know they were developing resistance to it, they didn't know they were taking it for nothing. So at the end of the first year of it I cut my dose down somewhat, and brought the info to my PCP, who took it to my onc.
Both my PCP and my onc, instead of being polite enough to treat the question (and me) respectfully by intelligent discussion, merely responded that "because I was probably menopausal [by this time], we will just put you on an aromatase inhibitor". I was appalled (and justifiably irritated) to have been put on a drug that had a 1/3 chance of risk of not being effective at all for me without any discussion in the first place, and then being treated like an idiot for bringing in the documentation for discussion--especially given that tamoxifen has many side effects and some additional risks.
It is possible that initially the tamoxifen was helpful to me, since my breast density was still dense at completion of rads after CAFx6 but disappeared by 3 months out from starting the tamoxifen. (Ditto for my sex life -- permanently.)
The research indicates that those HER2 positives who have a high AIB1 level are the ones who are likely to develop resistance to tamoxifen. I don't know why but there does not seem to be testing commonly available to determine whether one has a high AIB1 level.
What is concerning to me is that recently I saw some research that indicated that another group that has a high AIB1 level is the HR- group, which also tends to have a higher recurrence rate. The conclusion of the recent study is that maybe finding a way to knock down the AIB1 level may be worth targeting.
I don't know how "usable" this info is for those here, but it is just interesting to consider on an individual basis.