Is it at all surprising that, given these odds, many women who are judged to have a higher risk of getting breast cancer are refusing to take tamoxifen as a preventative? The only surprising thing is that anyone would find it surprising.
Here are the stats:
..[A]mong 1,000 similar women [judged to be at slightly higher risk than average of developing breast cancer], 19 would be expected to develop breast cancer over the next five years.
If those women all took tamoxifen, however, 9 of those women would avoid breast cancer ”” and, as a bonus, 13 would avoid broken bones from osteoporosis.
It is true that tamoxifen can have side effects, some of them serious. Among 1,000 similar 52-year-old women, the drug would be expected to cause 21 additional cases of endometrial cancer, a cancer of the uterine lining that is typically treatable when caught early. An additional 21 would develop blood clots, 31 would develop cataracts and 12 would develop sexual problems. And while more than half of the 1,000 women would naturally develop hormonal symptoms like hot flashes, changes in vaginal discharge or irregular periods, tamoxifen would cause those symptoms in about an additional 120 women.
So, there would be a significantly higher risk of developing another cancer (albeit one easier to successfully treat) and potentially fatal blood clots, as well as a much higher risk of developing a host of other symptoms that would impact negatively on quality of life. All to reduce a breast cancer risk from 19 per thousand to 10 per thousand. And the study doesn’t even say how many of these breast cancer cases would likely be treatable and survivable. Nor does it compare death rates in the groups; I wonder why, since that fact seems extremely relevant.
I’m not knocking the recommendation. I just think the correct decision is hardly a slam-dunk. Both prospects sound pretty dreadful, especially for women who are relatively young.


