Breast Cancer, Tamoxifen, and SSRIs
For some time, there has been concern about a possible negative interaction between Tamoxifen and some of the SSRIs (anti-depressants). Since hot flashes are a common side effect of Tamoxifen and low dose effexor (an SSRI) has been, for some women, a helpful medication to reduce their intensity, this concern has been wide-spread. The assumption has been that the dose to treat hot flashes, since it is well below the dose necessary to treat depression, was not a problem. This may be true.
Two studies presented at ASCO did not resolve this question. Here is a quote from a Medpage summary: If breast cancer survivors hoped to learn whether the antidepressants they're taking interfere with tamoxifen's ability to prevent a cancer recurrence, they were disappointed here this weekend. One major study said "yes" and another said "no." A review of almost 1000 breast cancer survivors in the US found that the concomitant use of Tamoxifen and an SSRI doubled the risk of recurrence in the first two years. A similar Dutch study found no such association. This is the link to that article:
Once again, this leaves us with unanswered questions and likely anxiety. I had several phone calls from panicked women this week who had read only the first study and worried that their health had been compromised. One of the realities of science is that a single study may or may not turn out to be the general truth (think of the old cliche: One sparrow does does make a summer.) There certainly will be more attention turned to this question, and we likely will have more information in years to come.
So, what are we supposed to do in the interim? The first answer, as always, is talk to your doctor about your concerns. The second is a reminder that there is no single treatment that always works for all women to control/minimize hot flashes. There are other things to try if you are nervous about continuing with effexor or another SSRI. The world's expert on hot flashes for women after breast cancer treatment is Charles Lorpinzi, MD at the Mayo Clinic. A summary of his research is that there is no magic bullet, but that there are a number of possibilities that may be helpful. I will write more in another blog; you can Google Dr. Loprinzi to learn more now.