Can we know if tamoxifen is working?

Yes!?  Maybe.  Initial results are suggestive.

In a study published in J Natl Cancer Inst, Cuzick, et al, report an intriguing finding http://jnci.oxfordjournals.org/content/103/9/744.full.  In a subset of patients from the International Breast Cancer Intervention Study (we call it IBIS-1) they compared breast density of those that got cancer who took tamoxifen and those that did not.  If breast density decreased by more than 10% on mammograms at 12-18 months, then the women in that group had 63% fewer cancers!  Less density reduction was associated with no risk reduction.  46% of women showed >10% reduction in density.

Admittedly, this was a small study and not controlled for all variables and defining breast density is operator dependent.  But, it is exciting to think that we might be able to save half of the women who might take tamoxifen long-term from the side effects.  If we knew it wasn't working for that woman, we could stop it or maybe try another medicine.

Another step closer to personalized medicine for breast cancer prevention!   In the mean time it probably is time for some exercise!


Together we can prevent 86,000 breast cancer cases this year!


This is general content and not personal medical advice.